#include 
    
     using namespace std;/*值传递，局部变量a和b的值确实在调用swap0时变化了，当结束时，他们绳命周期结束*/void swap0(int a, int b){	int tem = a;	a = b;	b = a;}/*没有初始化指针就开始用，该函数是有问题的*/void swap1(int *a, int *b){	int *tem;					/*注意tem没有分配内存*/	*tem = *a;	*a = *b;	*b = *tem;}/*函数内只是指针的变化，指针的值没有变化*/void swap2(int *a, int *b){	int *tem;	tem = a;	a = b;	b = tem;}/*指针传递实现两个数的交换*/void swap3(int *a, int *b){	int tem;	tem = *a;	*a = *b;	*b = tem;}/*指针传递实现两个数的交换*/void swap4(int &a, int &b){	int tem;		tem = a;	a = b;	b = tem;}int main(){	int num1 = 1;	int num2 = 2;		//swap0(num1, num2);		//swap1(&num1, &num2);	//swap2(&num1, &num2);	//swap3(&num1, &num2);    swap4(num1, num2);	cout << num1 << endl << num2 << endl;	return 0;}