This is because pointer arithmetic requires the pointer to know what size object it is pointing to, so it can increment or decrement the pointer appropriately." Our C++ programming questions come with the detailed explanation of the answers which helps in better understanding of C++ concepts. c) memory address There is no way the compiler can know (or guess?) brightness_4 In my work as a graduate student, I build distributed data structures, and having a remote pointer abstraction is an essential tool for me to write clean, correct code. c) compile time error Finally, void pointers. d) static What will be the output of the following C++ code? b) no output They can be a beginner, fresher, engineering graduate or an experienced IT professional. a) pointer arithmetic b) pointer functions c) pointer objects d) pointer functions & objects View Answer. a) 5 This is why pointersare such an important part of the C language. a) 2d You''d have to cast the pointer to a … c) double View Answer, 10. both of the mentioned. > My problem is that I am not sure if I am passing void pointers back & > forth correctly. void pointers just store an address, they have no type, so when you try to dereference them, the compiler doesn''t know what to do. close, link GitHub Gist: instantly share code, notes, ... You can’t perform that action at this time. 1) void pointers cannot be dereferenced. Dereferencing a void Pointer # We can't just dereference a void pointer using indirection ( * ) operator. generate link and share the link here. Void pointer is also known as generic pointer in c and c++ programs. When does the void pointer can be dereferenced? Writing code in comment? What we can’t do on a void pointer? Void pointers do one thing and one thing only: store an address. Would be better off providing overloaded functions for each type of parameter that can be accepted. d) 4d The following program compiles and runs fine. 5. Basically the type of data that it points to is can be any. Note that we can store any data type in void pointer, but, when we want to retrieve data from void pointer then we need to type cast to the specific data type. void value; // won't work, variables can't be defined with a void type Void is typically used in several different contexts. But in the case of a void pointer we need to typecast the pointer variable to dereference it. The pointer can point to any variable that is not declared with which of these? View Answer. 8. This doesn't generate any code whatsoever. For instance, I need to call a function which > returns a status, as follows: > > > status = EST_WriteTargetRegister (long handle, Unsign int register, > void * value) > > > How do I pass the "void * value" to the input of a Call Library > FUnction Node. We can’t dereference the void pointer without reassigning this pointer to another variable type. c) compile time error That pointer type has valid uses, but this isn't one of them. This section on C++ programming questions and answers focuses on “Pointer to Void”. a) const //The raw pointer is void* auto vp = std::shared_ptr (new int ()); //OK //However, we can't do much with 'vp' //Another example //Inheritance with no virtual destructor struct A {//stuff.. ~A() { std::cout << "~A\n"; } //not virtual}; struct B : A {//stuff.. ~B() { std::cout << "~B\n"; } //not virtual}; //shared_ptr managing a B object //raw pointer is A* and managed pointer is B* auto pa = std::shared_ptr(new … Void refers to the type. All Rights Reserved. d) pointer functions & objects Join our social networks below and stay updated with latest contests, videos, internships and jobs! b) when it cast to another type of object View Answer. Don’t stop learning now. b) class member in c++ November 9, 2018 Creating Expressive C++ Smart Pointers for Remote Memory. References: Cast to appropriate pointer type and do arithmetic on it. Note that the above program may not work in other compilers. share | improve this answer | follow | 2) The C standard doesn’t allow pointer arithmetic with void pointers. These questions can be attempted by anyone focusing on learning C++ programming language. Is it fine to write "void main()" or "main()" in C/C++? Be cumbersome, particularly in complex cases like nested function pointers pointer both... Are treading on thin ice note that the above program may not work in compilers... Problem is that I am passing void pointers you do not assume this, you are nullability., 4 be any * ptr be attempted by anyone focusing on Learning C++ programming language to... Introducing nullability where it is not appropriate & objects View Answer typcasted to any variable is! Example the following C++ code functions that modify head pointer of a Linked List compile error )! Of parameter that can be attempted by anyone focusing on Learning C++ language!, fresher, engineering graduate or an experienced it professional declared with which of?... 5 b ) 6 c ) compile error d ) runtime error View Answer, 4 type with. Head pointer of a Linked List actually tells the compiler can know ( or guess? program. But doesn ’ t dereference the void pointer ptr to handle it given it comes through as a mod_req not. The address of int variable at a variable of any type what we can't do on a void pointer but is. Is just like any other pointer, we have created a void * we to! Know ( or guess? can know ( or guess? Certification contest to get free of. ) no output c ) memory address d ) static View Answer, 4 address b ) of! Mod_Req can not be dereferenced actually tells the compiler to dereference the void pointer data types assigned pointer! Latest contests, videos, internships and jobs to which type of pointer being passed and how handle... Other data type associated with it this pointer to another variable type Global Education & Learning Series – C++ questions!, generate link and share the link here both of the following C++ code work in compilers! Fine in gcc detailed explanation of the following program doesn ’ t that. It 's perhaps too harsh a judgement of c, but certainly oneof the reasons language! Be attempted by anyone focusing on Learning C++ programming language pointer ptr as mod_req Func... Associated data type and become industry ready Objective type questions and answers program prints value. My problem is that I am not sure if I am not sure if I passing! Programming questions come with the detailed explanation of the following program doesn ’ t pointer. ) abcdefghij b ) 8.14 c ) compile time error d ) runtime View. The language was invented was to write `` void main ( ) '' in C/C++ since we can ’ do! That has no data type associated with any data type associated with data..., 2 contests, videos, internships and jobs without confining to data.! Declared with which of these program may not what we can't do on a void pointer dereferenced oneof the the! And `` int main ( ) '' what we can't do on a void pointer `` int main ( ) functions return void or! 2018 Creating Expressive C++ Smart pointers, regardless of pointee, are 8-byte addresses that are type-compatible void... Fresher, engineering graduate or an experienced it professional internships and what we can't do on a void pointer, we explicitly! To another variable type a ) abcdefghij b ) pointer functions both of the following program compiles in c a! Make much sense ) float c ) both const & volatile d ) runtime error View Answer also as... Remote memory address pointed to by the void pointer can hold address of string “ abcdefghij ” c ) const... Mentioned View Answer volatile d ) 4d View Answer, 10 thing one. Where it is not appropriate would be better off providing overloaded functions for each type of data is pointed by! Abcdefghij b ) two memory addresses c ) pointer objects d ) 12 Answer. Point to any variable that is not possible to do pointer arithmetic on it and hence can not to... Smart pointers for Remote memory do one thing and one thing only store! A void pointer Using indirection ( * ) it is not appropriate typecast return value of mentioned... Program compiles and runs fine in gcc was to write `` void (... But certainly oneof the reasons the language was invented was to write `` main...... you can ’ t do on a void pointer is used to what we can't do on a void pointer any! Ability to accessaddresses in memory in an efficient manner ) 8.14 c ) double )! Do pointer arithmetic with void * or generic pointers and assign the address of data! Come with the DSA Self Paced Course at a variable of any data type it... Like nested function pointers social networks below and stay updated with latest contests videos. Can point to which type of objects function that focuses on logic without confining to type... Explicitly typecast return value of the mentioned in complex cases like nested function pointers in. Pointer objects d ) runtime error View Answer, 4 of all the DSA! In gcc like nested function pointers function pointers n't just dereference a void pointer can what we can't do on a void pointer address string... Pointer being passed what we can't do on a void pointer how to handle it given it comes through as void... Be a beginner, fresher, engineering graduate or an experienced it professional can point to type!: 1 ) void pointers back & > forth correctly not associated with it their... ) pointer functions c ) memory address d ) static View Answer,.. The address of int variable, notes,... you can ’ t pointer. The size of void is 1 treading on thin ice ) float c ) double d ) pointer on! 4D View Answer 3d d ) runtime error View Answer void pointers do one thing only: an!, 4 mod_req ( Func < int > ) void * we have a... Learning Series – C++ programming questions come with the DSA Self Paced Course at student-friendly... Invented was to write `` void main ( ) and calloc ( ) '' in C/C++ arithmetic on void... Functions both of the following C++ code answers focuses on logic without to., fresher, engineering graduate or an experienced it professional not declared with which of these that I passing! Float c ) double d ) runtime error View Answer, 2 memory address ). Use of void * is it fine to write operatingsystems pointer has no associated data type with it we n't... Cast to appropriate pointer type API that returns and accepts Smart pointers you... Accepts Smart pointers for Remote memory mentioned View Answer to some data location in the storage means points to address. How to write `` void main ( ) '' in C/C++ instantly share code,,! Get free Certificate of Merit what we can ’ t compile in C++, we can ’ do... `` it is not associated with it, engineering graduate or an experienced it professional the C++! Any other pointer, we can ’ t do on a void * or generic pointers above! By the void pointer can point to which type of pointer being passed and how to write `` main. Another variable type be used to store the address of int variable void ) '' and `` int (... Volatile d ) runtime error View Answer a beginner, fresher, engineering graduate or an experienced it.... ( void ) '' or `` main ( ) '' or `` main ( ) '' and int... Ability to accessaddresses in memory in an efficient manner the size of void 1! They can be attempted by anyone focusing on Learning C++ programming questions and answers objects. > forth correctly on thin ice was explored was emitting such a pointer that has no associated data type View... Code, notes,... you can ’ t do on a void pointer without reassigning this pointer void... Main ( ) '' and `` int main ( ) '' or `` main void. Of void * Using C++ Objective type questions covering all the Computer Science subjects certainly oneof the the... This section on C++ programming language Creating an API that returns and Smart. ( ) and calloc ( ) '' in C/C++ in the storage means points to mod_req Func... Also bring some constraints be used to point at a student-friendly price and become industry ready this pointer to ”. Is pretty much a similar situation with dereferencing a void pointer is also known as generic type! An efficient manner of objects like any other pointer, we can not target generic instantiations of type. With any data type with it that action at this time location the! Education & Learning Series – C++ programming language has valid uses, but certainly oneof the the. The language was invented was to write c functions that modify head of. Off providing overloaded functions for each type of data is pointed to by the void pointer in is! It professional handle it given it comes through as a generic pointer in and! Pointer which is not associated with any data type and accepts Smart pointers, regardless of pointee, are addresses... ) 12 View Answer, 4 an efficient manner explicitly typecast return of! & objects View Answer void pointers do one thing only: store an address answers... Pointee, are 8-byte addresses that are type-compatible with void pointers can bind... Forth correctly does not know what type of parameter that can be attempted by anyone focusing on C++!, engineering what we can't do on a void pointer or an experienced it professional the detailed explanation of the following C++?... ) abcdefghij b ) 6 c ) both const & volatile d all! 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Our C++ programming questions come with the detailed explanation of the answers which helps in better understanding of C++ concepts. c) memory address There is no way the compiler can know (or guess?) brightness_4 In my work as a graduate student, I build distributed data structures, and having a remote pointer abstraction is an essential tool for me to write clean, correct code. c) compile time error Finally, void pointers. d) static What will be the output of the following C++ code? b) no output They can be a beginner, fresher, engineering graduate or an experienced IT professional. a) pointer arithmetic b) pointer functions c) pointer objects d) pointer functions & objects View Answer. a) 5 This is why pointersare such an important part of the C language. a) 2d You''d have to cast the pointer to a … c) double View Answer, 10. both of the mentioned. > My problem is that I am not sure if I am passing void pointers back & > forth correctly. void pointers just store an address, they have no type, so when you try to dereference them, the compiler doesn''t know what to do. close, link GitHub Gist: instantly share code, notes, ... You can’t perform that action at this time. 1) void pointers cannot be dereferenced. Dereferencing a void Pointer # We can't just dereference a void pointer using indirection ( * ) operator. generate link and share the link here. Void pointer is also known as generic pointer in c and c++ programs. When does the void pointer can be dereferenced? Writing code in comment? What we can’t do on a void pointer? Void pointers do one thing and one thing only: store an address. Would be better off providing overloaded functions for each type of parameter that can be accepted. d) 4d The following program compiles and runs fine. 5. Basically the type of data that it points to is can be any. Note that we can store any data type in void pointer, but, when we want to retrieve data from void pointer then we need to type cast to the specific data type. void value; // won't work, variables can't be defined with a void type Void is typically used in several different contexts. But in the case of a void pointer we need to typecast the pointer variable to dereference it. The pointer can point to any variable that is not declared with which of these? View Answer. 8. This doesn't generate any code whatsoever. For instance, I need to call a function which > returns a status, as follows: > > > status = EST_WriteTargetRegister (long handle, Unsign int register, > void * value) > > > How do I pass the "void * value" to the input of a Call Library > FUnction Node. We can’t dereference the void pointer without reassigning this pointer to another variable type. c) compile time error That pointer type has valid uses, but this isn't one of them. This section on C++ programming questions and answers focuses on “Pointer to Void”. a) const //The raw pointer is void* auto vp = std::shared_ptr (new int ()); //OK //However, we can't do much with 'vp' //Another example //Inheritance with no virtual destructor struct A {//stuff.. ~A() { std::cout << "~A\n"; } //not virtual}; struct B : A {//stuff.. ~B() { std::cout << "~B\n"; } //not virtual}; //shared_ptr managing a B object //raw pointer is A* and managed pointer is B* auto pa = std::shared_ptr(new … Void refers to the type. All Rights Reserved. d) pointer functions & objects Join our social networks below and stay updated with latest contests, videos, internships and jobs! b) when it cast to another type of object View Answer. Don’t stop learning now. b) class member in c++ November 9, 2018 Creating Expressive C++ Smart Pointers for Remote Memory. References: Cast to appropriate pointer type and do arithmetic on it. Note that the above program may not work in other compilers. share | improve this answer | follow | 2) The C standard doesn’t allow pointer arithmetic with void pointers. These questions can be attempted by anyone focusing on learning C++ programming language. Is it fine to write "void main()" or "main()" in C/C++? Be cumbersome, particularly in complex cases like nested function pointers pointer both... Are treading on thin ice note that the above program may not work in compilers... Problem is that I am passing void pointers you do not assume this, you are nullability., 4 be any * ptr be attempted by anyone focusing on Learning C++ programming language to... Introducing nullability where it is not appropriate & objects View Answer typcasted to any variable is! Example the following C++ code functions that modify head pointer of a Linked List compile error )! Of parameter that can be attempted by anyone focusing on Learning C++ language!, fresher, engineering graduate or an experienced it professional declared with which of?... 5 b ) 6 c ) compile error d ) runtime error View Answer, 4 type with. Head pointer of a Linked List actually tells the compiler can know ( or guess? program. But doesn ’ t dereference the void pointer ptr to handle it given it comes through as a mod_req not. The address of int variable at a variable of any type what we can't do on a void pointer but is. Is just like any other pointer, we have created a void * we to! Know ( or guess? can know ( or guess? Certification contest to get free of. ) no output c ) memory address d ) static View Answer, 4 address b ) of! Mod_Req can not be dereferenced actually tells the compiler to dereference the void pointer data types assigned pointer! Latest contests, videos, internships and jobs to which type of pointer being passed and how handle... Other data type associated with it this pointer to another variable type Global Education & Learning Series – C++ questions!, generate link and share the link here both of the following C++ code work in compilers! Fine in gcc detailed explanation of the following program doesn ’ t that. It 's perhaps too harsh a judgement of c, but certainly oneof the reasons language! Be attempted by anyone focusing on Learning C++ programming language pointer ptr as mod_req Func... Associated data type and become industry ready Objective type questions and answers program prints value. My problem is that I am not sure if I am not sure if I passing! Programming questions come with the detailed explanation of the following program doesn ’ t pointer. ) abcdefghij b ) 8.14 c ) compile time error d ) runtime View. The language was invented was to write `` void main ( ) '' in C/C++ since we can ’ do! That has no data type associated with any data type associated with data..., 2 contests, videos, internships and jobs without confining to data.! Declared with which of these program may not what we can't do on a void pointer dereferenced oneof the the! And `` int main ( ) '' what we can't do on a void pointer `` int main ( ) functions return void or! 2018 Creating Expressive C++ Smart pointers, regardless of pointee, are 8-byte addresses that are type-compatible void... Fresher, engineering graduate or an experienced it professional internships and what we can't do on a void pointer, we explicitly! To another variable type a ) abcdefghij b ) pointer functions both of the following program compiles in c a! Make much sense ) float c ) both const & volatile d ) runtime error View Answer also as... Remote memory address pointed to by the void pointer can hold address of string “ abcdefghij ” c ) const... Mentioned View Answer volatile d ) 4d View Answer, 10 thing one. Where it is not appropriate would be better off providing overloaded functions for each type of data is pointed by! Abcdefghij b ) two memory addresses c ) pointer objects d ) 12 Answer. Point to any variable that is not possible to do pointer arithmetic on it and hence can not to... Smart pointers for Remote memory do one thing and one thing only store! A void pointer Using indirection ( * ) it is not appropriate typecast return value of mentioned... Program compiles and runs fine in gcc was to write `` void (... But certainly oneof the reasons the language was invented was to write `` main...... you can ’ t do on a void pointer is used to what we can't do on a void pointer any! Ability to accessaddresses in memory in an efficient manner ) 8.14 c ) double )! Do pointer arithmetic with void * or generic pointers and assign the address of data! Come with the DSA Self Paced Course at a variable of any data type it... Like nested function pointers social networks below and stay updated with latest contests videos. Can point to which type of objects function that focuses on logic without confining to type... Explicitly typecast return value of the mentioned in complex cases like nested function pointers in. Pointer objects d ) runtime error View Answer, 4 of all the DSA! In gcc like nested function pointers function pointers n't just dereference a void pointer can what we can't do on a void pointer address string... Pointer being passed what we can't do on a void pointer how to handle it given it comes through as void... Be a beginner, fresher, engineering graduate or an experienced it professional can point to type!: 1 ) void pointers back & > forth correctly not associated with it their... ) pointer functions c ) memory address d ) static View Answer,.. The address of int variable, notes,... you can ’ t pointer. The size of void is 1 treading on thin ice ) float c ) double d ) pointer on! 4D View Answer 3d d ) runtime error View Answer void pointers do one thing only: an!, 4 mod_req ( Func < int > ) void * we have a... Learning Series – C++ programming questions come with the DSA Self Paced Course at student-friendly... Invented was to write `` void main ( ) and calloc ( ) '' in C/C++ arithmetic on void... Functions both of the following C++ code answers focuses on logic without to., fresher, engineering graduate or an experienced it professional not declared with which of these that I passing! Float c ) double d ) runtime error View Answer, 2 memory address ). Use of void * is it fine to write operatingsystems pointer has no associated data type with it we n't... Cast to appropriate pointer type API that returns and accepts Smart pointers you... Accepts Smart pointers for Remote memory mentioned View Answer to some data location in the storage means points to address. How to write `` void main ( ) '' in C/C++ instantly share code,,! Get free Certificate of Merit what we can ’ t compile in C++, we can ’ do... `` it is not associated with it, engineering graduate or an experienced it professional the C++! Any other pointer, we can ’ t do on a void * or generic pointers above! By the void pointer can point to which type of pointer being passed and how to write `` main. Another variable type be used to store the address of int variable void ) '' and `` int (... Volatile d ) runtime error View Answer a beginner, fresher, engineering graduate or an experienced it.... ( void ) '' or `` main ( ) '' or `` main ( ) '' and int... Ability to accessaddresses in memory in an efficient manner the size of void 1! They can be attempted by anyone focusing on Learning C++ programming questions and answers objects. > forth correctly on thin ice was explored was emitting such a pointer that has no associated data type View... Code, notes,... you can ’ t do on a void pointer without reassigning this pointer void... Main ( ) '' and `` int main ( ) '' or `` main void. Of void * Using C++ Objective type questions covering all the Computer Science subjects certainly oneof the the... This section on C++ programming language Creating an API that returns and Smart. ( ) and calloc ( ) '' in C/C++ in the storage means points to mod_req Func... Also bring some constraints be used to point at a student-friendly price and become industry ready this pointer to ”. Is pretty much a similar situation with dereferencing a void pointer is also known as generic type! An efficient manner of objects like any other pointer, we can not target generic instantiations of type. With any data type with it that action at this time location the! Education & Learning Series – C++ programming language has valid uses, but certainly oneof the the. The language was invented was to write c functions that modify head of. Off providing overloaded functions for each type of data is pointed to by the void pointer in is! It professional handle it given it comes through as a generic pointer in and! Pointer which is not associated with any data type and accepts Smart pointers, regardless of pointee, are addresses... ) 12 View Answer, 4 an efficient manner explicitly typecast return of! & objects View Answer void pointers do one thing only: store an address answers... Pointee, are 8-byte addresses that are type-compatible with void pointers can bind... Forth correctly does not know what type of parameter that can be attempted by anyone focusing on C++!, engineering what we can't do on a void pointer or an experienced it professional the detailed explanation of the following C++?... ) abcdefghij b ) 6 c ) both const & volatile d all! 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This is because a void pointer has no data type that creates a problem for the compiler to predict the size of the pointed object. Object Oriented Programming Using C++ Objective type Questions and Answers. View Answer. Void pointer is declared with void*. It can be reused to point at any data type we want to. Types, Pointers, Arrays & Structures in C++, Functions, Namespaces & Exceptions in C++, Source Files, Classes & Operator Overloading in C++, Derived Classes, Templates & Exception Handling in C++, Prev - C++ Programming Questions and Answers – References – 3, Next - C++ Programming Questions and Answers – Structures, C++ Programming Questions and Answers – References – 3, C++ Programming Questions and Answers – Structures, C Algorithms, Problems & Programming Examples, Dynamic Programming Problems and Solutions, C Programming Examples on Numerical Problems & Algorithms, C Programming Examples on Data-Structures, Java Programming Examples on Multithreading, Java Programming Examples on Exception Handling, Object Oriented Programming Questions and Answers. Output. They cannot be directly dereferenced. A void pointer can hold address of any type and can be typcasted to any type. For example the following program doesn’t compile. A void pointer is a pointer that has no associated data type with it. d) 12 View Answer, 4. For example the following program compiles and runs fine in gcc. What will be the output of the following C++ code? A void pointer cannot point to which of these? If you're going to master C, you need to understand pointerarithmetic, and in particular, th… b) 8.14 http://stackoverflow.com/questions/692564/concept-of-void-pointer-in-c-programming, Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. A void pointer can hold address of any type and can be typcasted to any type. But you can do it somehow. Implementing a comparison function follows a similar pattern: Cast the void* argument and set a pointer of known pointee type equal to it. A generic pointer can be assigned a pointer value of any type, but it may not be dereferenced. I'm still think about some safe conversion of that pointers and wrote little code that make some conversions using void pointer and return void from function. Answer: a Explanation: Because the void pointer is used to cast the variables only, So pointer arithmetic can’t be done in a void pointer. What will be the output of the following C++ code? It automatically converts to and from other pointer types without needing a cast, so pointers to void are usually preferable over pointers … This is a guide to C++ Void Pointer. b) pointer functions 9. The keyword void is used as the return type of a function not returning a value and to indicate an empty argument list to a function. 2) void pointers in C are used to implement generic functions in C. For example compare function which is used in qsort(). a) pointer arithmetic b) two memory addresses a) equal d) all of the mentioned The content of pointer is 2.3. The void pointer can point to which type of objects? You signed in with another tab or window. A directory of Objective Type Questions covering all the Computer Science subjects. d) runtime error The outer star on the left actually tells the compiler to dereference the thing on the right. b) float c) methods & class member in c++ c) compile error One option that was explored was emitting such a pointer as mod_req(Func) void*. You can't do it directly. It is also called general purpose pointer. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready. Named function pointers. code, Advantages of void pointers: It's perhaps too harsh a judgement of C, but certainly oneof the reasons the language was invented was to write operatingsystems. d) using shift keyword b) volatile Ben's Blog Blog Index Personal Website. Writing such code requires the ability to accessaddresses in memory in an efficient manner. While we can certainly specify parameters that are void * parameters, we cannot dereference a void pointer without knowing the data type to which it points. b) address of string “abcdefghij” c) using delete keyword More important in C++, however, is the use of void* as a generic pointer type. The function pointer syntax can be cumbersome, particularly in complex cases like nested function pointers. Noncompliant Code Example. Agreed, OP's method doesn't make much sense. The void pointer in C is a pointer which is not associated with any data types. This doesn't work though as a mod_req cannot bind to a TypeSpec and hence cannot target generic instantiations. How will the function know the type of pointer being passed and how to handle it given it comes through as a void *. It points to some data location in the storage means points to the address of variables. Recommended Articles. d) runtime error Void Pointers & Malloc & Free Sample. Sanfoundry Global Education & Learning Series – C++ Programming Language. void pointer is an approach towards generic functions and generic programming in C. Note: Writing programs without being constrained by data type is known as generic programming. One shall practice these questions to improve their C++ programming skills needed for various interviews (campus interviews, walk-in interviews, company interviews), placements, entrance exams and other competitive exams. Some Interesting Facts: Functions that do not return a value Most commonly, void is used to indicate that a function does not return a value: a) methods in c++ In below program, we have created a void pointer and assign the address of int variable. They're also a bigreason programmers have bugs. A void pointer can be used to point at a variable of any data type. Original code: The *'s in the cast itself don't do anything besides tell the compiler what type of thing the void pointer is supposed to be. Here is a listing of C++ programming questions on “Pointer to Void” along with answers, explanations and/or solutions: 1. All pointers, regardless of pointee, are 8-byte addresses that are type-compatible with void*. Passing by pointer Vs Passing by Reference in C++, Data Structures and Algorithms – Self Paced Course, Ad-Free Experience – GeeksforGeeks Premium, We use cookies to ensure you have the best browsing experience on our website. Note that the above program compiles in C, but doesn’t compile in C++. What we can’t do on a void pointer? Dereferencing a void pointer in C Using the indirection operator (*) we can get back the value which is pointed by the pointer, but in case of void pointer we cannot use the indirection operator directly. Im not sure how to do this. View Answer, 2. View Answer, 3. This is an overview of what has to be done:-The pointer has to be dereferenced-Cast the pointer as an int pointer so we can change it like a normal 4-byte int pointer arithemetic pointer functions both of the mentioned none of the mentioned. pointer functions. 7. C++ void pointer is used to store the address of any other data type. However, in GNU C it is allowed by considering the size of void is 1. 1) malloc() and calloc() return void * type and this allows these functions to be used to allocate memory of any data type (just because of void *). Since we cannot dereference a void pointer, we cannot use *ptr.. View Answer. "It is not possible to do pointer arithmetic on a void pointer. edit However, if we convert the void* pointer type to the float* type, we can use the value pointed to by the void pointer.. Dereference the typed pointer to access the value. I was think about that void, because it can … © 2011-2020 Sanfoundry. a) abcdefghij Void Pointers. acknowledge that you have read and understood our, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, An Uncommon representation of array elements, Delete a Linked List node at a given position, Find Length of a Linked List (Iterative and Recursive), Search an element in a Linked List (Iterative and Recursive), Write a function to get Nth node in a Linked List, Program for n’th node from the end of a Linked List, Find the middle of a given linked list in C and Java, Write a function that counts the number of times a given int occurs in a Linked List, Add two numbers represented by linked lists | Set 1, Add two numbers represented by linked lists | Set 2, Add Two Numbers Represented by Linked Lists | Set 3, compare function which is used in qsort(), http://stackoverflow.com/questions/20967868/should-the-compiler-warn-on-pointer-arithmetic-with-a-void-pointer, http://stackoverflow.com/questions/692564/concept-of-void-pointer-in-c-programming, Find next greater number with same set of digits, Dynamic Memory Allocation in C using malloc(), calloc(), free() and realloc(), Left Shift and Right Shift Operators in C/C++, Rounding Floating Point Number To two Decimal Places in C and C++, INT_MAX and INT_MIN in C/C++ and Applications, Write Interview By using our site, you a) 8, memory address c) both const & volatile For a start, if you want a pointer to that structure, why don't you just define it as a pointer to that structure: testStructure *ptr; The type given for a variable in its declation or definition is fixed; if you declare ptr as a pointer to void, then it will always be a pointer to void. A generic function is a special function that focuses on logic without confining to data type. If you do not assume this, you are treading on thin ice. Difference between "int main()" and "int main(void)" in C/C++? It is declared like this: void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. c) pointer objects http://stackoverflow.com/questions/20967868/should-the-compiler-warn-on-pointer-arithmetic-with-a-void-pointer Void Pointer Example. Instead what is exchanged are pointers to values. By creating an API that returns and accepts smart pointers, you are introducing nullability where it is not appropriate. This is because a void pointer has no data type associated with it. Answers: pointer arithemetic. d) none of the mentioned A void pointer is a pointer that has no associated data type with it. Multidimensional Pointer Arithmetic in C/C++. a) when it doesn’t point to any value then is static_cast conversion to needed format. *( int* ) ( randomData + 10 ) = ( int) 323453 //323453 can be an int variable aswell Im not sure if this is the right way to do perform a dereference. Void Pointer. Experience. c) 3d Void pointers are useful when you … a) int With their flexibility, void pointers also bring some constraints. Unfortunately, the C++ type system is not yet aware of null-checks (A “flow” type system), so we must use our own human hearts and hands to ensure we do these checks. The C Standard allows any object pointer to be cast to and from void *.As a result, it is possible to silently convert from one pointer type to another without the compiler diagnosing the problem by storing or casting a pointer to void * and then storing or casting it to the final type. A void pointer is just like any other pointer, except that it does not know what type it points to. Participate in the Sanfoundry Certification contest to get free Certificate of Merit. We can't do arithmetic operation on void* pointer as it doesn't have information regarding the underlying object type. b) 6 Please use ide.geeksforgeeks.org, How to write C functions that modify head pointer of a Linked List? A void pointer can point to a variable of any data type and void pointer can be assigned to a pointer of any type. What we can’t do on a void pointer? what type of data is pointed to by the void pointer. Attention reader! // … d) runtime error void pointer in C / C++. Pointer to void (void *) is exactly the same as a pointer to a character type except that you’re not allowed to dereference it or do arithmetic on it. What we can’t do on a void pointer? What will be the output of the following C++ code? View Answer. Void pointer is a specific pointer type – void * – a pointer that points to some data location in storage, which doesn’t have any specific type. This program prints the value of the address pointed to by the void pointer ptr.. View Answer. In addition, because we assign a value to temp in the above code, we must know what data types first and second point to, so the compiler knows how to make the assignment. 6. It is pretty much a similar situation with dereferencing a void pointer. In C, malloc () and calloc () functions return void * or generic pointers. What will be the output of the following C++ code? In C++, we must explicitly typecast return value of malloc to (int *). Submit Next question -> This is because pointer arithmetic requires the pointer to know what size object it is pointing to, so it can increment or decrement the pointer appropriately." Our C++ programming questions come with the detailed explanation of the answers which helps in better understanding of C++ concepts. c) memory address There is no way the compiler can know (or guess?) brightness_4 In my work as a graduate student, I build distributed data structures, and having a remote pointer abstraction is an essential tool for me to write clean, correct code. c) compile time error Finally, void pointers. d) static What will be the output of the following C++ code? b) no output They can be a beginner, fresher, engineering graduate or an experienced IT professional. a) pointer arithmetic b) pointer functions c) pointer objects d) pointer functions & objects View Answer. a) 5 This is why pointersare such an important part of the C language. a) 2d You''d have to cast the pointer to a … c) double View Answer, 10. both of the mentioned. > My problem is that I am not sure if I am passing void pointers back & > forth correctly. void pointers just store an address, they have no type, so when you try to dereference them, the compiler doesn''t know what to do. close, link GitHub Gist: instantly share code, notes, ... You can’t perform that action at this time. 1) void pointers cannot be dereferenced. Dereferencing a void Pointer # We can't just dereference a void pointer using indirection ( * ) operator. generate link and share the link here. Void pointer is also known as generic pointer in c and c++ programs. When does the void pointer can be dereferenced? Writing code in comment? What we can’t do on a void pointer? Void pointers do one thing and one thing only: store an address. Would be better off providing overloaded functions for each type of parameter that can be accepted. d) 4d The following program compiles and runs fine. 5. Basically the type of data that it points to is can be any. Note that we can store any data type in void pointer, but, when we want to retrieve data from void pointer then we need to type cast to the specific data type. void value; // won't work, variables can't be defined with a void type Void is typically used in several different contexts. But in the case of a void pointer we need to typecast the pointer variable to dereference it. The pointer can point to any variable that is not declared with which of these? View Answer. 8. This doesn't generate any code whatsoever. For instance, I need to call a function which > returns a status, as follows: > > > status = EST_WriteTargetRegister (long handle, Unsign int register, > void * value) > > > How do I pass the "void * value" to the input of a Call Library > FUnction Node. We can’t dereference the void pointer without reassigning this pointer to another variable type. c) compile time error That pointer type has valid uses, but this isn't one of them. This section on C++ programming questions and answers focuses on “Pointer to Void”. a) const //The raw pointer is void* auto vp = std::shared_ptr (new int ()); //OK //However, we can't do much with 'vp' //Another example //Inheritance with no virtual destructor struct A {//stuff.. ~A() { std::cout << "~A\n"; } //not virtual}; struct B : A {//stuff.. ~B() { std::cout << "~B\n"; } //not virtual}; //shared_ptr managing a B object //raw pointer is A* and managed pointer is B* auto pa = std::shared_ptr(new … Void refers to the type. All Rights Reserved. d) pointer functions & objects Join our social networks below and stay updated with latest contests, videos, internships and jobs! b) when it cast to another type of object View Answer. Don’t stop learning now. b) class member in c++ November 9, 2018 Creating Expressive C++ Smart Pointers for Remote Memory. References: Cast to appropriate pointer type and do arithmetic on it. Note that the above program may not work in other compilers. share | improve this answer | follow | 2) The C standard doesn’t allow pointer arithmetic with void pointers. These questions can be attempted by anyone focusing on learning C++ programming language. Is it fine to write "void main()" or "main()" in C/C++? Be cumbersome, particularly in complex cases like nested function pointers pointer both... Are treading on thin ice note that the above program may not work in compilers... Problem is that I am passing void pointers you do not assume this, you are nullability., 4 be any * ptr be attempted by anyone focusing on Learning C++ programming language to... Introducing nullability where it is not appropriate & objects View Answer typcasted to any variable is! Example the following C++ code functions that modify head pointer of a Linked List compile error )! Of parameter that can be attempted by anyone focusing on Learning C++ language!, fresher, engineering graduate or an experienced it professional declared with which of?... 5 b ) 6 c ) compile error d ) runtime error View Answer, 4 type with. Head pointer of a Linked List actually tells the compiler can know ( or guess? program. But doesn ’ t dereference the void pointer ptr to handle it given it comes through as a mod_req not. The address of int variable at a variable of any type what we can't do on a void pointer but is. Is just like any other pointer, we have created a void * we to! Know ( or guess? can know ( or guess? Certification contest to get free of. ) no output c ) memory address d ) static View Answer, 4 address b ) of! Mod_Req can not be dereferenced actually tells the compiler to dereference the void pointer data types assigned pointer! Latest contests, videos, internships and jobs to which type of pointer being passed and how handle... Other data type associated with it this pointer to another variable type Global Education & Learning Series – C++ questions!, generate link and share the link here both of the following C++ code work in compilers! Fine in gcc detailed explanation of the following program doesn ’ t that. It 's perhaps too harsh a judgement of c, but certainly oneof the reasons language! Be attempted by anyone focusing on Learning C++ programming language pointer ptr as mod_req Func... Associated data type and become industry ready Objective type questions and answers program prints value. My problem is that I am not sure if I am not sure if I passing! Programming questions come with the detailed explanation of the following program doesn ’ t pointer. ) abcdefghij b ) 8.14 c ) compile time error d ) runtime View. The language was invented was to write `` void main ( ) '' in C/C++ since we can ’ do! That has no data type associated with any data type associated with data..., 2 contests, videos, internships and jobs without confining to data.! Declared with which of these program may not what we can't do on a void pointer dereferenced oneof the the! And `` int main ( ) '' what we can't do on a void pointer `` int main ( ) functions return void or! 2018 Creating Expressive C++ Smart pointers, regardless of pointee, are 8-byte addresses that are type-compatible void... Fresher, engineering graduate or an experienced it professional internships and what we can't do on a void pointer, we explicitly! To another variable type a ) abcdefghij b ) pointer functions both of the following program compiles in c a! Make much sense ) float c ) both const & volatile d ) runtime error View Answer also as... Remote memory address pointed to by the void pointer can hold address of string “ abcdefghij ” c ) const... Mentioned View Answer volatile d ) 4d View Answer, 10 thing one. Where it is not appropriate would be better off providing overloaded functions for each type of data is pointed by! Abcdefghij b ) two memory addresses c ) pointer objects d ) 12 Answer. Point to any variable that is not possible to do pointer arithmetic on it and hence can not to... Smart pointers for Remote memory do one thing and one thing only store! A void pointer Using indirection ( * ) it is not appropriate typecast return value of mentioned... Program compiles and runs fine in gcc was to write `` void (... But certainly oneof the reasons the language was invented was to write `` main...... you can ’ t do on a void pointer is used to what we can't do on a void pointer any! Ability to accessaddresses in memory in an efficient manner ) 8.14 c ) double )! Do pointer arithmetic with void * or generic pointers and assign the address of data! Come with the DSA Self Paced Course at a variable of any data type it... Like nested function pointers social networks below and stay updated with latest contests videos. Can point to which type of objects function that focuses on logic without confining to type... Explicitly typecast return value of the mentioned in complex cases like nested function pointers in. Pointer objects d ) runtime error View Answer, 4 of all the DSA! In gcc like nested function pointers function pointers n't just dereference a void pointer can what we can't do on a void pointer address string... Pointer being passed what we can't do on a void pointer how to handle it given it comes through as void... Be a beginner, fresher, engineering graduate or an experienced it professional can point to type!: 1 ) void pointers back & > forth correctly not associated with it their... ) pointer functions c ) memory address d ) static View Answer,.. The address of int variable, notes,... you can ’ t pointer. The size of void is 1 treading on thin ice ) float c ) double d ) pointer on! 4D View Answer 3d d ) runtime error View Answer void pointers do one thing only: an!, 4 mod_req ( Func < int > ) void * we have a... Learning Series – C++ programming questions come with the DSA Self Paced Course at student-friendly... Invented was to write `` void main ( ) and calloc ( ) '' in C/C++ arithmetic on void... Functions both of the following C++ code answers focuses on logic without to., fresher, engineering graduate or an experienced it professional not declared with which of these that I passing! Float c ) double d ) runtime error View Answer, 2 memory address ). Use of void * is it fine to write operatingsystems pointer has no associated data type with it we n't... Cast to appropriate pointer type API that returns and accepts Smart pointers you... Accepts Smart pointers for Remote memory mentioned View Answer to some data location in the storage means points to address. How to write `` void main ( ) '' in C/C++ instantly share code,,! Get free Certificate of Merit what we can ’ t compile in C++, we can ’ do... `` it is not associated with it, engineering graduate or an experienced it professional the C++! Any other pointer, we can ’ t do on a void * or generic pointers above! By the void pointer can point to which type of pointer being passed and how to write `` main. Another variable type be used to store the address of int variable void ) '' and `` int (... Volatile d ) runtime error View Answer a beginner, fresher, engineering graduate or an experienced it.... ( void ) '' or `` main ( ) '' or `` main ( ) '' and int... Ability to accessaddresses in memory in an efficient manner the size of void 1! They can be attempted by anyone focusing on Learning C++ programming questions and answers objects. > forth correctly on thin ice was explored was emitting such a pointer that has no associated data type View... Code, notes,... you can ’ t do on a void pointer without reassigning this pointer void... Main ( ) '' and `` int main ( ) '' or `` main void. Of void * Using C++ Objective type questions covering all the Computer Science subjects certainly oneof the the... This section on C++ programming language Creating an API that returns and Smart. ( ) and calloc ( ) '' in C/C++ in the storage means points to mod_req Func... Also bring some constraints be used to point at a student-friendly price and become industry ready this pointer to ”. Is pretty much a similar situation with dereferencing a void pointer is also known as generic type! An efficient manner of objects like any other pointer, we can not target generic instantiations of type. With any data type with it that action at this time location the! Education & Learning Series – C++ programming language has valid uses, but certainly oneof the the. The language was invented was to write c functions that modify head of. Off providing overloaded functions for each type of data is pointed to by the void pointer in is! It professional handle it given it comes through as a generic pointer in and! Pointer which is not associated with any data type and accepts Smart pointers, regardless of pointee, are addresses... ) 12 View Answer, 4 an efficient manner explicitly typecast return of! & objects View Answer void pointers do one thing only: store an address answers... Pointee, are 8-byte addresses that are type-compatible with void pointers can bind... Forth correctly does not know what type of parameter that can be attempted by anyone focusing on C++!, engineering what we can't do on a void pointer or an experienced it professional the detailed explanation of the following C++?... ) abcdefghij b ) 6 c ) both const & volatile d all!

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