对为什么我的代码不会输出文本感到困惑？

Question

这是我第一次在这里发帖，如果帖子格式不正确，我深表歉意。我是 C++ 新手，正在寻求帮助。

在大约第 18 行之后，我似乎无法弄清楚是什么阻止了我的代码。它处理第一个 cout 和 cin，但不继续处理下一个 cout？

如果您输入一个键，它将运行 if/then 语句中列出的所有条件并完成。但是，我在这里的目标是让计算机生成一个随机数，然后要求我输入 (Y/N)。给定输入，它要么应该生成另一个随机数，要么结束。

使用编译器不会产生错误，所以我现在有点傻眼了。

如果有任何帮助，我将不胜感激，谢谢。

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#include<iostream.h>

int comp;

using namespace std;
int main ()
{


comp= 1+(rand() % 10);

randomnumber:
string again;

cout <<"The computer chose this random number: "<< comp << endl;
cin >> comp;

cout << "Would you like to run this again? Y/N" << endl;
cin >> again;



if((again == "y")||(again == "Y"))
{
    goto randomnumber;
}

else if((again == "n")||(again == "N"))
{
 cout << "OK" << endl;
}

else if((again != "y")||(again != "Y")||(again != "n")||(again !="N"))
{
 cout << "Please type Y or N" << endl;

}
    return 0;
}

Answer 1

首先让我们看一下代码应该如何满足您的要求。

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#include<iostream.h>
//int comp; No need for comp to be a global variable here.
using namespace std;
int main ()
{
    int comp;
    randomnumber://if you were to use goto, the label should have been here.
    comp= 1+(rand() % 10);
    //randomnumber: avoid goto statements at all if possible.
    //string again; No need for it to be a string. 
    char again;
    cout <<"The computer chose this random number: "<< comp << endl;
    //cin >> comp; since you want computer to generate a random no, why ask the  user for it? 
    cout << "Would you like to run this again? Y/N" << endl;
    cin >> again;
    if((again == "y")||(again == "Y"))
    {
        goto randomnumber;
    }
    else if((again == "n")||(again == "N"))
    {
             cout << "OK" << endl;        
    }
    else if((again != "y")||(again != "Y")||(again != "n")||(again !="N"))
    {
             cout << "Please type Y or N" << endl;

    }
    return 0;
 }

现在让我们看看如何以一种更不复杂、更简单的方式做到这一点。

#include<iostream.h> //#include<iostream> if No such file error.
#include<time.h> // for seeding rand()
#include<stdlib.h> // for rand
using namespace std;
int main()
{
    srand(time(NULL)); //seeding rand()
    while(true)
    {
        int comp=1+(rand() % 10);
        cout <<"The computer chose this random number: "<< comp << endl;
        cout<<"Would you like to run this again?Y/N"<< endl;
        char choice;
        cin>>choice;
        if ((choice == 'N')|| (choice =='n'))
        {
            cout<<"OK"<< endl;
            break;
        }
        else
            while(choice!='y' && choice!='Y') // forcing user to enter a valid input.
            {
                cout<<"Please type Y or N" << endl;
                cin>>choice;
            }
    }
    return 0;
}

我希望这会有所帮助。