幾種交換兩個數函數（swap函數）的寫法和解析

#include <iostream>using namespace std;/*值傳遞，局部變數a和b的值確實在調用swap0時變化了，當結束時，他們繩命周期結束*/void swap0(int a, int b){int tem = a;a = b;b = a;}/*沒有初始化指標就開始用，該函數是有問題的*/void swap1(int *a, int *b){int *tem;/*注意tem沒有分配記憶體*/*tem = *a;*a = *b;*b = *tem;}/*函數內只是指標的變化，指標的值沒有變化*/void swap2(int *a, int *b){int *tem;tem = a;a = b;b = tem;}/*指標傳遞實現兩個數的交換*/void swap3(int *a, int *b){int tem;tem = *a;*a = *b;*b = tem;}/*指標傳遞實現兩個數的交換*/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;}