The pointer has no size. It is just pointing to some memory location that contains your data. You'd have to keep track of how big you made the array.
If you want to find out how big a data type is, you are looking for sizeof(). That will tell you the size reserved for an int, float, char, etc.
Here's an example...
Code:
#include <stdio.h>
main()
{
printf("float: %d\n" , sizeof(float));
printf("int: %d\n" , sizeof(int));
printf("double: %d\n" , sizeof(double));
printf("long: %d\n" , sizeof(long));
printf("long long: %d\n" , sizeof(long long));
printf("long double: %d\n" , sizeof(long double));
}