When is a void pointer used? in C programming

When is a void pointer used?

A void pointer is used for working with raw memory or for passing a pointer to an unspecified type.
Some C code operates on raw memory. When C was first invented, character pointers (char *) were used
for that. Then people started getting confused about when a character pointer was a string, when it was a
character array, and when it was raw memory.

For example, strcpy() is used to copy data from one string to another, and strncpy() is used to copy at most
a certain length string to another:
char *strcpy( char *str1, const char *str2 );
char *strncpy( char *str1, const char *str2, size_t n );
memcpy() is used to move data from one location to another:
void *memcpy( void *addr1, void *addr2, size_t n );
void pointers are used to mean that this is raw memory being copied. NUL characters (zero bytes) aren’t
significant, and just about anything can be copied. Consider the following code:
#include “thingie.h” /* defines struct thingie */
struct thingie *p_src, *p_dest;
/* ... */
memcpy( p_dest, p_src, sizeof( struct thingie) * numThingies );
This program is manipulating some sort of object stored in a struct thingie. p1 and p2 point to arrays, or
parts of arrays, of struct thingies. The program wants to copy numThingies of these, starting at the one
pointed to by p_src, to the part of the array beginning at the element pointed to by p_dest. memcpy() treats
p_src and p_dest as pointers to raw memory; sizeof( struct thingie) * numThingies is the number of
bytes to be copied.

The keyword void had been invented to mean “no value,” so void* was adopted to mean “a pointer to some
thing, I don’t know what exactly.” void pointers are often used with function pointers.

Cross Reference:

VII.5: What is a void pointer?
VII.14: When would you use a pointer to a function?