按值传递和引用传递的区别

来源：互联网发布：淘宝差评小二介入编辑：程序博客网时间：2024/05/16 13:06

按值传递：在方法中使用这个变量将会复制一个临时变量，返回时会销毁这个临时变量

引用传递：不需要创建临时变量和销毁临时变量，节约时间和空间，如果可以选择，优先选择引用传递

 #include"stdio.h"#include <iostream>using namespace std;class CopyTest{private :char *name;int len;static int  num_name;public:CopyTest();CopyTest(char *str);~CopyTest();friend std::ostream & operator<<(std::ostream &os,const CopyTest  &st);//getName();CopyTest(CopyTest & copyA);};CopyTest::CopyTest(){cout<<"使用copyTest()创建"<<"\n";num_name++;len=4 ;name=new char[len];strcpy(name,"c++");}int CopyTest::num_name=0;CopyTest::CopyTest(CopyTest & copyA){cout<<"使用copyTest(CopyTest & copyA)创建"<<copyA.name<<"\n";num_name++;len=copyA.len ;name=new char[len+1];strcpy(name,copyA.name);}CopyTest::CopyTest(char *str){cout<<"使用copyTest(char *str)创建"<<str<<"\n";num_name++;len=strlen(str);name=new char[len+1];strcpy(name,str);}CopyTest::~CopyTest(){cout<<"销毁"<<name<<"\n";num_name--;}void getName(CopyTest sb){cout<<"name:"<<sb<<"\n";}std::ostream &  operator<<(std::ostream  & os,const CopyTest &st){os<<st.name ;return os;}int main(){   CopyTest test("test");   getName1(test);//在getName中使用CopyTest时先调用复制构造函数创建一个临时的CopyTest，返回时调用析构方法销毁这个临时的CopyTest   cout<<test;getchar();return 0;}

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