Why do we have pointers other than void

Question

I know that we have different pointers like int, float, and char. A void pointer is the only pointer which can hold all o

Answer 1

Dead simple:

void* p;
*p; // compile error!

Or to put it in words; a void pointer can not be dereferenced.

Perhaps you should rename the question why do we have pointers, or rather don't and just search for that question on SO.

Answer 2

When You use pointer to float or int (for example) compiler knows how many bytes it should take from memory (sizeof(int) for int* for example).

With void You would have to tell each time to compiler how many bytes it have to take (by writing (int*)some_void_ptr for example.

But this is great simplification.

Answer 3

int o = 12;
void *i = &o;

How would you access the int that i points to if there were only void pointers and no int*. You might know that on your platform an int is 4 bytes so you could memcpy 4 bytes from the start of whatever the void* points to into a temporary int and then use that. But that's not very convenient.

Or given a

struct Pair {
   char *first;
   char *second;
};

how useful would a void pointer to struct Pair be ? You'd likely want to access its first member and that's a lot of work if you couldn't have a pointer to a struct Pair.

Answer 4

Type safety. Defining the type of pointers helps the compiler find errors where you are trying to use data of the wrong type through a pointer. That's the reason C has types in the first place.

Answer 5

Two Words: Type Safety

There's a little tidbit on type safety (or lack thereof) in C on Wikipedia that might shed some light for you.

Answer 6

Is there any other reason that pointers other than void are present in C language?

They are an awesome way to handle memory chunks freely. : )