C语言函数参数ParamType param与ParamType &param的区别

#include<stdio.h>
#include<stdlib.h>


void test1(int a){
	printf("test1 method address:%d\n",&a);
	printf("test1 method %d\n",a);
	a = 2;
}

void test2(int& a){
	printf("test2 method address:%d\n",&a);
	printf("test2 method %d\n",a);
	a = 2;
}

void test3(int* &p){
	printf("method test3 a's address:%d\n",&p);
}

void test4(int* p){
	printf("method test4 a's address:%d\n",&p);
}



int main(){
	int a = 1;
	printf("main method a's address:%d\n",&a);
	test1(a);
	printf("after method test1 a = %d\n",a);
	test2(a);
	printf("after method test2 a = %d\n",a);


	int* pa = &a;
	printf("main method pa's address:%d\n",&pa);
	test3(pa);
	test4(pa);

	return 0;
}