论述
主函数中的构造体变量作为非主函数的参数时,若只是将构造体变量名传与非主函数, 那就意味着仅是将其值传递给了非主函数外部,相当于在非主函数外部复制粘贴了一个新的构造体(此处称之为X),这个新构造体X与主函数中的构造体(此处称之为Y)是互相独立的,但它们二者的初始成员值都雷同.
struct SSS{ ...};void NonMain(SSS X){ // X & Y的初始成员值都雷同, 地址却相异 ...}int mian(){ SSS Y; NonMain(Y); return 0;}根据上述代码,如果在NonMain函数中扭转了构造体变量外部的值,当NonMain函数运行完结后,程序返回主函数时,主函数中原有的构造体变量外部不会有丝毫变动.
这是因为构造体变量名自身不是地址, 非主函数内所操作的构造体变量的地址,并非主函数中的构造体变量的地址.
因而,正确的构造体变量传参加非主函数时,须要先取出构造体变量的地址当作指针,再将指针传与非主函数.
代码示例
#include <string>#include <cstring>#include <iostream>#include <queue>using namespace std;typedef struct TimesRecord{ int year; int month; int day;} times;void initializationError(TimesRecord date_record){ date_record.year = 2015; date_record.month = 5; date_record.day = 18; cout << "initializationError.&date_record: " << &date_record << endl;}void alterError(TimesRecord date_record, int newYear, int newMonth, int newDay){ date_record.year = newYear; date_record.month = newMonth; date_record.day = newDay; cout << "alterError.&date_record: " << &date_record << endl;}/* ----------------------------------------------------------------------------- */void initializationCorrect(TimesRecord &date_record){ date_record.year = 2015; date_record.month = 5; date_record.day = 18; cout << "initializationCorrect.&date_record: " << &date_record << endl;}void alterCorrect(TimesRecord &date_record, int newYear, int newMonth, int newDay){ date_record.year = newYear; date_record.month = newMonth; date_record.day = newDay; cout << "alterCorrect.&date_record: " << &date_record << endl;}int main(int argc, char const *argv[]){ TimesRecord t; int newYear = 2006; int newMonth = 9; int newDay = 22; initializationError(t); cout << "Error initialization: "; cout << t.year << "-" << t.month << "-" << t.day << endl; cout << "main.&t: " << &t << endl; cout << endl; alterError(t, newYear, newMonth, newDay); cout << "Error Alter: "; cout << t.year << "-" << t.month << "-" << t.day << endl; cout << "main.&t: " << &t << endl; cout << endl; initializationCorrect(t); cout << "Correct initialization: "; cout << t.year << "-" << t.month << "-" << t.day << endl; cout << "main.&t: " << &t << endl; cout << endl; alterCorrect(t, newYear, newMonth, newDay); cout << "Correct Alter: "; cout << t.year << "-" << t.month << "-" << t.day << endl; cout << "main.&t: " << &t << endl; return 0;}运行后果
initializationError.&date_record: 0x7ffc498004b0Error initialization: -5234528-22046-1233126896main.&t: 0x7ffc498004e8alterError.&date_record: 0x7ffc498004b0Error Alter: -5234528-22046-1233126896main.&t: 0x7ffc498004e8initializationCorrect.&date_record: 0x7ffc498004e8Correct initialization: 2015-5-18main.&t: 0x7ffc498004e8alterCorrect.&date_record: 0x7ffc498004e8Correct Alter: 2006-9-22main.&t: 0x7ffc498004e8