Any type of pointer variable takes the same memory bytes in the memory, 
because they are used to store the memory addresses on other type of variables

the size of different types of pointers

内存地址
32位系统 内存地址占4个字节
64位系统 内存地址占8个字节

32位系统寻址范围是2的32次方



#include "stdio.h"
int main(){
  printf("sizeof(char*)   = %d\n",sizeof(char*));
  printf("sizeof(int*)    = %d\n",sizeof(int*));
  printf("sizeof(long*)   = %d\n",sizeof(long*));
  printf("sizeof(double*) = %d\n",sizeof(double*));
  return 0;
}

sizeof(char*)   = 8
sizeof(int*)    = 8
sizeof(long*)   = 8
sizeof(double*) = 8