By using our site, you Is this just a no-op to prevent the function from being optimized away? Or does it actually do anything? According to C standard, the pointer to void shall have the same representation and alignment requirements as a pointer to a character type. Jan 5 '07 #3. 2) The C standard doesn’t allow pointer arithmetic with void pointers. A void pointer is a pointer that has no associated data type with it. A memory location can be cast, for example, from MyClass* to void* and back again to MyClass*. ... Any pointer type: void* null: Any pointer type : Explicit pointer conversion is used to perform conversions, for which there is no implicit conversion, by using a cast expression. very very helpful. Furthermore, the conversion is implicit in C (unlike C++), that is, the following should compile as well. The reason for this is simple: malloc returns void* and not int*.While in C it's legal to assign void* to int* without a cast, in C++ it isn't.. Why the difference? reinterpret_cast can convert between two pointers to different functions only. In C, malloc() and calloc() functions return void * or generic pointers. It's not calling a function and casting its return value as void - that would require a couple more parentheses. Before you dereference a void pointer it must be typecasted to appropriate pointer type. We use cookies to ensure you have the best browsing experience on our website. The void pointer in C is a pointer which is not associated with any data types. It is also called general purpose pointer. Don’t stop learning now. Where as *((int*)ptr) dereferences the typecasted void pointer variable.ptr=&b; // Assigning address of float to void pointer.printf("The value of float variable is= %f",*( (float*) ptr) );Another important point you should keep in mind about void pointers is that – pointer arithmetic can not be performed in a void pointer. When a typed pointer is cast to a void pointer, the contents of the memory location are unchanged. Here comes the importance of a “void pointer”. However, pointers may be type cast from one type to another type.In the following code lines, A is an int type variable, D is variable of type double, and ch is a variable of type char. Rather, the void pointer must first be explicitly cast to another pointer type before it is dereferenced. A void pointer can hold address of any type and can be typcasted to any type.Note that the above program compiles in C, but doesn’t compile in C++. A void pointer is nothing but a pointer variable declared using the reserved word in C ‘void’. A void pointer in c is called a generic pointer, it has no associated data type. (void)(foo); It's not a void pointer cast - that would be straightforward. In C, malloc() and calloc() functions return void * or generic pointers. Well, let us start with C. The official "bible" of C, "The C Programming Language, 2nd edition" by Kernighan and Ritchie states in section A.6.8: Any pointer to an object may be converted to type void* without loss of information.

Before you apply pointer arithmetic in void pointers make sure to provide a proper typecast first otherwise you may get unexcepted results. A pointer to void can store the address of any object (not function), and, in C, is implicitly converted to any other object pointer type on assignment, but it must be explicitly cast if dereferenced. We saw that pointer values may be assigned to pointers of same type. However, in GNU C it is allowed by considering the size of void is 1. Get hold of all the important DSA concepts with the The void pointer in C is a pointer which is not associated with any data types. We use cookies to ensure you have the best browsing experience on our website. For example the following program compiles and runs fine in …

Note that the above program compiles in C, but doesn’t compile in C++. Well, let us start with C. The official "bible" of C, "The C Programming Language, 2nd edition" by Kernighan and Ritchie states in section A.6.8: Any pointer to an object may be converted to type void* without loss of information. Why the difference? Here it is in context. A void pointer can point to a variable of any data type. A void pointer can hold address of any type and can be typcasted to any type.Note that the above program compiles in C, but doesn’t compile in C++. In C++, we must explicitly typecast return value of malloc to (int *).Note that the above program may not work in other compilers.Please write comments if you find anything incorrect, or you want to share more information about the topic discussed aboveAttention reader!

Before going further it will be good if you refresh about pointers by reading – A pointer variable declared using a particular data type can not  hold the location address of variables of other data types. It can store the address of any type of object and it can be type-casted to any type.