Why is the data type needed in pointer declarations?

Question

As far as I know about data types in C/C++, while declaring a variable, we need to declare its data type, which tells the compiler to reserve the number of bytes in the memo

Answer 1

First of all the size and representation of the pointers themselves aren't always the same for different types. It's just something that happens on many implementations.

Second, when using pointers you don't care about the size of the pointers themselves. You need the size of the pointed type.

For example, try this:

int var[5];
char *c = (char *)var;
int  *x = var;

printf("%p\n%p\n", p + 1, x + 1);

You'll see pointer arithmetic strongly depends on the size of the pointed type.