Question

当我运行我的程序时，它第一次工作，读取正确的输入并将输出写入我的输出文件但是一旦我再次运行它就不会写任何文件只是空白，即使它读取一切都正确。我似乎无法理解它在哪里搞乱或者我真的想知道。这两个图像是我的第一次和第二次运行，只是在第二次运行后我的输出文件是空白的。

first run

second run

#include<iostream>
#include<iostream>
#include<cstdlib>
#include<time.h>
#include<fstream>
#include<string>
using namespace std;



int main()
{
    int i=0;
    int number; // The correct number
    int guess=0;  // The user's guess
    int numGuesses=0; // The number of times the user has guessed
    string lines;
    string player;
    ifstream ifile;
    ofstream ofile;
    //ofstream myfile;
    //
    string names[10];
    int scores[10];
    ifile.open("high_score.txt");

    string first_last_name;
    string temp;
    int score;
    int index=0;
    string title;
    bool topten=false;


    cout <<"Welcome to the number guessing game. The top 10 best scores so far are: "<<endl;
    while(!ifile.eof())
    {

        //getline(ifile,lines);
        ifile >>first_last_name;
        //cout << first_last_name;
        ifile >> temp;
        first_last_name.append(" ");
        first_last_name.append(temp);
        ifile >> score;
        names[index]=first_last_name;
        scores[index++]=score;

    }
    cout << "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"<<endl;
    for (int i=0; i < 10; i++)
    {
        cout << names[i] << " " << scores[i] <<endl;

    }
    // Seed the random generator.
    srand(static_cast<int> (time(NULL)));

    // Generate a random number between 1 and 100.
    number = (rand() % 100) + 1;

    cout << "Let's play the number guessing game! What is your name? " <<endl; 
    getline(cin,player);
    cout << endl;   
    while(guess!=number)
    {
        cout << "guess the number the computer randomly picked between 1 - 100: ";
        cin >> guess;
        numGuesses++;

        // Check if the user has guessed the correct number.
        // If not, tell him if his guess is too low or too high
        if(number > guess)
        {
            cout << "sorry, your guess is too low" << endl;
        }
        else if(number < guess)
        {
            cout << "sorry, your guess is too high" << endl;
        }
        else
        {
            cout << "You guessed right!!!!"<<endl;
            cout << "You win!!!" << endl;
            break;
        }

    }
       cout << "It took you "<< numGuesses << " guesses "<< player<< endl;
////////////////////////////////////////////////////////////////////////
       if (numGuesses<4)
       {
       cout << "Amazing! Or was it luck" << endl;
       }
       else if(numGuesses<6)
       {
           cout <<"That's a very good score..." <<endl;
       }

       else if (numGuesses<8)
       {
        cout << "That's pretty good but you can do better..." << endl;
       }

       else if ( numGuesses<10)
       {
       cout << "Not too shabby, but not too good either..."<< endl;
       }

       else
       {
       cout << "What a terrible score!..." << endl;
       }

    for(int i=0; i < 10; i++)
    {
        if(numGuesses <= scores[i])
        {
            for( int k=9;k>i;k--)
            {   
                scores[k]=scores[k-1];
                names[k]=names[k-1];
            }

            scores[i]=numGuesses;
            names[i]=player;
            topten=true;
            break;
        }


    }
    if(topten==true)
    {

        cout << "Hey, you made it to the top ten , Congratzzzzzzzz!!!!" <<endl;
    }
    ofile.open("high_score.txt");
    for(int i=0;i<10;i++)
    {
        ofile <<"\t"<< names[i] << " " << scores[i] <<endl;
        ofile << endl;

    }

    return 0;
}

Answer 1

您需要在打开输出文件之前关闭输入文件，因为它们都指向同一个文件。

关闭可以通过调用ifile.close()显式完成，也可以在打开输出文件之前隐式使ifile超出范围。

后者可以这样做：

{
    ifstream ifile;
    ifile.open("high_score.txt");
    // do stuff with ifile
}
ofstream ofile;
ofile.open("high_score.txt");
// do stuff with ofile

Answer 2

ifile.close（）和ofile.close（）在哪里你应该关闭其他你的流将进入无效状态。

.EOF在读取文件时导致Seg Fault：FIXXED

2 个答案: