c++ - 为什么它停止并以退出代码 11 结束？

Question

我不知道它为什么停在那里并以退出代码 11 结束。它应该一直运行到我发出命令为止。

#include <iostream>
#include <string>
#include <fstream>
using namespace std;


void record(string name, string phoneNum, int count);

// main
int main() {
    cout << " Welcome to use the Phone Contact Systerm " << endl;
    string name;
    string phoneNum;
    int count = 0;
    string signToStop;
    cout << " Please enter name and phone number " << endl;
    while ( cin >> name >> phoneNum){
        cout << " If you want to start the program, enter start "         << endl;
        cout << " If you want to quit the program, enter quit " <<     endl;
        cin >> signToStop;
        if (signToStop == "start"){
            record(name, phoneNum, count);
            cout << " Please enter name and phone number " << endl;
        }
        else if ( signToStop == "quit" ){
            break;
        }
        cout << count << endl;
        count++;


    }
}

// record all name info into Name set and record all phone numbers         into PhoneNum set
void record(string name, string phoneNum, int count){
    string Name[] = {};
    string PhoneNum[] = {};
    Name[count] = {name};
    PhoneNum[count] = {phoneNum};

    // now start to record all the info into .txt document

    ofstream phoneFile;
    phoneFile.open("contact.txt");
    phoneFile << name << "  " << phoneNum << endl;
}

结果是:

 Welcome to use the Phone Contact Systerm 

 Please enter name and phone number 

Molly 5307609829

 If you want to start the program, enter start 

 If you want to quit the program, enter quit 

start

 Please enter name and phone number 

0

Lilyi 44080809829

 If you want to start the program, enter start 

 If you want to quit the program, enter quit 

start

Process finished with exit code 11

Answer 1

问题出在这部分:

void record(string name, string phoneNum, int count){
    string Name[] = {};
    string PhoneNum[] = {};
    Name[count] = {name};
    PhoneNum[count] = {phoneNum};

    //...
}

这在 C++ 中很糟糕，因为 string Name[] = {}; 和其他类似的东西并没有按照您认为的那样去做。他们创建一个空的字符串数组。自变量 length arrays are not a thing in C++ , 这会创建一个 buffer overflow ，这is undefined behavior . That's bad .

使用 std::vector相反:

void record(string name, string phoneNum){
    std::vector<std::string> Name;
    std::vector<std::string> PhoneNum;
    Name.push_back(name);
    PhoneNum.push_back(phoneNum);

    //...
}

---

附言您的程序中还有另一个错误。即Name和PhoneNum会在每次函数退出时被销毁。如果这是故意的，那很好。如果你想保留一个运行记录列表，那是不好的。您可以使用 static variable解决这个问题:

void record(string name, string phoneNum){
    static std::vector<std::string> Name;
    static std::vector<std::string> PhoneNum;
    //...
}