對引用和指針使用以及函數返回引用和指針類型的理解

原創

2020-02-20 16:47

#include "stdafx.h"
#include <iostream>
using namespace std;
int globalJ =999;

//返回值
int test1()
{
    int j =1;
    cout<<"in test1(),[return value] the varaible j's address :"<<&j<<endl;

    return j;
}

//使用局部變量，返回引用
int& test2()
{
int j =998;
cout<<"in test2(),[use field variable and return reference] the local varaible J's address :"<<&j<<endl;
cout<<"in test2(),[use field variable and return reference] the local varaible J's value :"<<j<<endl;

return j;
}

//使用全局變量，返回引用
int& test3()
{

    cout<<"in test3(),[use global variable and return reference] the varaible globalJ's address :"<<&globalJ<<endl;

    return globalJ;
}

//返回指針
int* test4()
{
    int j =998;
    cout<<"in test4(),[use field variable and return pointer] the local varaible J's address :"<<&j<<endl;
cout<<"in test4(),[use field variable and return pointer] the local varaible J's value :"<<j<<endl;

return &j;
}
//返回指針
int* test5()
{
    cout<<"in test5()[use global variable and return pointer] , the varaible globalJ's address :"<<&globalJ<<endl;
    return &globalJ;
}

int main(int argc, char* argv[])
{
    printf("Hello functions!/n");

    int testresultvalue =0;
    testresultvalue = test1();
    cout<<"testResultValue address :"<<&testresultvalue <<endl;
    cout<<"testResultValue value:"<<testresultvalue<<endl;
    cout<<"slit line----------------------------------"<<endl;

    int & testResultReference = test2();
    cout<<"testResultReference address :"<<&testResultReference <<endl;
    cout<<"testResultReference value:"<<testResultReference<<endl;
    cout<<"slit line----------------------------------"<<endl;

    testResultReference = test3();
    cout<<"testResultReference address :"<<&testResultReference <<endl;
    cout<<"testResultReference value:"<<testResultReference<<endl;
    testResultReference = 4;
    cout<<"reset to 4"<<endl;
    cout<<"testResultReference address :"<<&testResultReference <<endl;
    cout<<"testResultReference value:"<<testResultReference<<endl;

    cout<<"slit line----------------------------------"<<endl;

    int & testResultReference2 = test3();
    cout<<"testResultReference2 address :"<<&testResultReference2 <<endl;
    cout<<"testResultReference2 value:"<<testResultReference2<<endl;
    cout<<"slit line----------------------------------"<<endl;

    int* testResultPtr;
    testResultPtr = test4();
    cout<<"testResult address :"<<testResultPtr <<endl;
    cout<<"testResult value:"<<*testResultPtr<<endl;
    cout<<"slit line----------------------------------"<<endl;

    testResultPtr = test5();
    cout<<"testResult address :"<<testResultPtr <<endl;
    cout<<"testResult value:"<<*testResultPtr<<endl;
    cout<<"slit line----------------------------------"<<endl;

    int temp;
    cin>>temp;

    return 0;
}