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

Assume that this code compiles without error (as you would like):

int a;
int b = 42;
void * d = &b;

a = *d;

What should be the value of a?

Now with this one:

int a;
float b = 42.0;
void * d = &b;

a = *d;

What do you expect in a?

Actually the type specifies how should the pointed area be interpreted. You should specify int * in the first example and float * in the second one, instead of void *.