C++ C++；试图从txt文件中删除使用过的行

我试图从一个txt文件（questions.txt）中删除使用过的行，并将它们放入另一个文件（usedQuestions.txt），但现在代码只是删除questions.txt，没有将任何内容放入temp.txt或重命名它；并且没有在usedQuestions.txt中输入任何内容

这是我的代码：

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

int main () {

    // Loop infinitely
    for (int i = 1; i > 0; i++) {

        // Files
        ifstream txtFile("questions.txt");
        ofstream usedQuestions("usedQuestions.txt");
        ofstream tempFile("temp.txt");

        // Strings, ints etc.
        string question;
        string temp;
        unsigned int lineNum = 1;
        int requestedLineNum;

        // User requests line
        cin >> requestedLineNum;
        cout << "You have requested question number: " << requestedLineNum << endl;

        // Go through lines until the correct line is found
        while (getline(txtFile, question))
        {

            //If the line number is correct, output question
            if (lineNum == requestedLineNum)
            {
                cout << "Your question is: " << question << endl;

                // Write to temporary file, doesn't work?
                while (getline(txtFile, temp)) {
                    tempFile << temp;
                }

                // Write to file with used questions
                usedQuestions << question;
            }

            // Set up for while loop to go through lines
            lineNum++;
        }

        // Close and remove questions.txt, rename temp.txt to questions.txt
        txtFile.close();
        remove("questions.txt");
        rename("temp.txt", "questions.txt");
    }
    return 0;
}

#包括
#包括
#包括
使用名称空间std；
int main（）{
//无限循环
对于（int i=1；i>0；i++）{
//档案
ifstream txtFile（“questions.txt”）；
流使用的问题（“usedQuestions.txt”）；
流tempFile（“temp.txt”）；
//字符串、整数等。
字符串问题；
字符串温度；
无符号整数lineNum=1；
int requestedLineNum；
//用户请求行
cin>>请求的LineNum；
cout我刚刚为您完成了代码编写，我将解释一下：

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

//This objects can be declared one time
ofstream usedQuestions("usedQuestions.txt");

// Strings, ints etc.
string question, temp;
unsigned int lineNum = 1;
int requestedLineNum;

int main () {

    // Loop infinitely
    while(true) {//Use while(true) or for(;;) for endless loops

        // Files
        ifstream txtFile("questions.txt");
        ofstream tempFile("temp.txt");
        lineNum = 1;

        // User requests line
        cout << "Write a line number (-1 for exit): ";//when you run the code what you think you have to do? It isn't written...
        cin >> requestedLineNum;

        //this is a possibility to exit from the main loop
        if(requestedLineNum==-1) break;
        else {
            cout << "You have requested question number: " << requestedLineNum << endl;

            // Go through lines until the correct line is found
            while(getline(txtFile, question))
            {//while it doesn't reach the end of the file read a line from the file

                //If the line number is correct, output question
                if (lineNum == requestedLineNum)
                {
                    cout << "Your question is: \"" << question << "\"\n" << endl;//You've forgotten the endl - your code generate one line with all questions!

                    // Write to file with used questions
                    usedQuestions << question << endl;
                }
                else tempFile << question << endl;//if it isn't the selected question step to the next line, so the question won't appear at the next iteration

                // Set up for while loop to go through lines
                lineNum++;
            }
            // Close and remove questions.txt, rename temp.txt to questions.txt
            txtFile.close();
            remove("questions.txt");
            rename("temp.txt", "questions.txt");
        }
    }
    return 0;
}

或

而不是

 for (int i = 1; i > 0; i++) //it needs a variable (i)

3-我写了：

cout << "Write a line number (-1 for exit): ";
cin >> requestedLineNum;

在运行程序时轻松退出循环

5-我添加了

 << endl;

可能行号永远不等于requestedlinenum在测试时，您可能应该删除
重命名（）
和
删除（）
您从未关闭
临时文件
。因此
重命名（“temp.txt”，“questions.txt”）；
可能不起作用。您复制文件的代码似乎在所选行之后复制了所有内容。代码很漂亮，但似乎不起作用。我得到了一个usedQuestions.txt文件，其中包含正确的问题，但我也得到了一个空的temp.txt文件，其中questions.txt被删除。我不明白temp.txt必须包含什么。我知道ght这是一个临时文件来移动questionsTrue。因此，在最后，它应该包含除已使用的问题之外的所有问题。事实并非如此。事实上，它是空的。那么temp.txt将与questions.txt相同？也许它是无用的…很抱歉这么晚了，它应该是相同的，但没有已使用的问题。
cout << "Write a line number (-1 for exit): ";
cin >> requestedLineNum;

 if(requestedLineNum==-1) break;
 else {...

 << endl;

//If the line number is correct, output question
if (lineNum == requestedLineNum)
{
    cout << "Your question is: " << question << endl;

    // Write to temporary file, doesn't work? //  <--
    while (getline(txtFile, temp)) {          //  <--
        tempFile << temp;                     //  <--
    }                                         //  <--

   // Write to file with used questions
   usedQuestions << question;
}

//If the line number is correct, output question
if (lineNum == requestedLineNum) {
     cout << "Your question is: \"" << question << "\"\n" << endl;

     // Write to file with used questions
     usedQuestions << question << endl;
}
    else tempFile << question << endl;

// Set up for while loop to go through lines
lineNum++;