C++指针的长度

所有的指针的长度都是4,包括空指针

#include <iostream>
#include <stdio.h>
#include<memory.h>
using namespace std;

#define null NULL

int f1(int a)
{
	return a;
}
void f2(int a)
{
	cout<<a<<endl;
}
int main(int argc,char* argv[])
{
	freopen("C:\\Users\\zzzzz\\Desktop\\1.txt", "r", stdin);
	double* pd;
	char* pc;
	float* pf;
	long long* pll;
	int* pi;
	void* pv;
	int (*fi)(int);
	void (*fv)(int);
	cout<< sizeof(pd)<<endl;
	cout<<sizeof(pc)<<endl;
	cout<<sizeof(pf)<<endl;
	cout<<sizeof(pll)<<endl;
	cout<<sizeof(pi)<<endl;
	cout<<sizeof(pv)<<endl;
	cout<<sizeof(fi)<<endl;
	cout<<sizeof(fv)<<endl;
	cout<<sizeof(null)<<endl;
	return 0;
}