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C语言 结构体作为参数和返回值使用

方案一:结构体变量作为参数,进行传值。

    编译器需要拷贝,不影响origin value,使用成员操作符(.)直接访问

/*********************************************************************** 版权所有 (C)2017, Wang maochun。** 文件名称:travel.cpp* 文件标识:无* 内容摘要:主要演示结构体作为参数以及返回值 * 其它说明:"传值” * 当前版本:V1.0* 作    者:Wang maochun* 完成日期:2017.7.23***********************************************************************/#include <iostream>struct travel_time{    int hours;    int mins;};const int Mins_per_hr = 60;travel_time sum(travel_time t1,travel_time t2);void show_time(travel_time t);int main(){    using namespace std;    travel_time day1 = {5,45};  //5 hours 45 minutes    travel_time day2 = {4,55};  //4 housr 55 minutes        travel_time trip = sum(day1,day2);    cout << "Two-day total:";    show_time(trip);        travel_time day3 = {4,32};    cout << "Three-day total:";    show_time(sum(trip,day3));         return 0;}travel_time sum(travel_time t1,travel_time t2){    travel_time total;        total.mins = (t1.mins + t2.mins) % Mins_per_hr;    total.hours = (t1.hours + t2.hours) + (t1.mins + t2.mins) / Mins_per_hr;        return total;}void show_time(travel_time t){    using namespace std;    cout << t.hours << "hours,"         << t.mins  << "minutes\n";} 

运行结果:

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方案二:结构体指针作为参数,传地址。

    编译器不需要拷贝,和main函数采用相同地址。为了不影响origin value,使用const修饰

    使用指针指向结构体操作符(->)间接访问

/*********************************************************************** 版权所有 (C)2017, Wang maochun。** 文件名称:travel.cpp* 文件标识:无* 内容摘要:主要演示结构体作为参数以及返回值 * 其它说明:"传地址” * 当前版本:V1.0* 作    者:Wang maochun* 完成日期:2017.7.23***********************************************************************/#include <iostream>struct travel_time{    int hours;    int mins;};const int Mins_per_hr = 60;travel_time sum(travel_time* t1,travel_time* t2);void show_time(travel_time* t);int main(){    using namespace std;    travel_time day1 = {5,45};  //5 hours 45 minutes    travel_time day2 = {4,55};  //4 housr 55 minutes        travel_time trip = sum(&day1,&day2);    cout << "Two-day total:";    show_time(&trip);        travel_time day3 = {4,32};    cout << "Three-day total:";    travel_time trip1 =sum(&trip,&day3);    show_time(&(trip1));         return 0;}travel_time sum(travel_time* t1,travel_time* t2){    travel_time total;        total.mins = (t1->mins + t2->mins) % Mins_per_hr;    total.hours = (t1->hours + t2->hours) + (t1->mins + t2->mins) / Mins_per_hr;        return total;}void show_time(travel_time* t){    using namespace std;    cout << t->hours << "hours,"         << t->mins  << "minutes\n";} 

结果和方案一相同。

 

出现的错误:

show_time(&(sum(&day1,&day2)));这样写时,出现taking address of temporary fpermissive错误。
原因是:
Your middle result which is a temporary variable since it will disappear
If you assign the result of sum(&day1,&day2) to a variable then it will no longer be a temporary and you can then take the address of it.
因此,不能对未赋值的临时变量取地址

C语言 结构体作为参数和返回值使用