C++ Trying to delete used line from txt file [closed]

-3

I'm trying to delete used lines from a txt file (questions.txt) and put them into another file (usedQuestions.txt), but right now the code just deletes questions.txt, doesn't put anything in temp.txt or renames it; and doesn't put anything in usedQuestions.txt

This is my code:

#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;

}

asked Nov 20 '18 at 20:58

Artain

closed as off-topic by πάντα ῥεῖ, Jean-François Fabre, Gert Arnold, Killzone Kid, Pearly Spencer Nov 20 '18 at 23:43

This question appears to be off-topic. The users who voted to close gave this specific reason:

"Questions seeking debugging help ("why isn't this code working?") must include the desired behavior, a specific problem or error and the shortest code necessary to reproduce it in the question itself. Questions without a clear problem statement are not useful to other readers. See: How to create a Minimal, Complete, and Verifiable example." – πάντα ῥεῖ, Jean-François Fabre, Gert Arnold, Killzone Kid, Pearly Spencer

If this question can be reworded to fit the rules in the help center, please edit the question.

Maybe lineNumber is never equal to requestedLineNum

– drescherjm
Nov 20 '18 at 21:41

While testing you probably should remove the rename() and remove()

– drescherjm
Nov 20 '18 at 21:42

You never closed the tempFile. so the rename("temp.txt", "questions.txt"); may not work.

– drescherjm
Nov 20 '18 at 21:42

Your code that copies the file seems to copy everything after the selected line.

– drescherjm
Nov 20 '18 at 21:45

add a comment |

-3

This is my code:

#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;

}

asked Nov 20 '18 at 20:58

Artain

closed as off-topic by πάντα ῥεῖ, Jean-François Fabre, Gert Arnold, Killzone Kid, Pearly Spencer Nov 20 '18 at 23:43

This question appears to be off-topic. The users who voted to close gave this specific reason:

"Questions seeking debugging help ("why isn't this code working?") must include the desired behavior, a specific problem or error and the shortest code necessary to reproduce it in the question itself. Questions without a clear problem statement are not useful to other readers. See: How to create a Minimal, Complete, and Verifiable example." – πάντα ῥεῖ, Jean-François Fabre, Gert Arnold, Killzone Kid, Pearly Spencer

If this question can be reworded to fit the rules in the help center, please edit the question.

Maybe lineNumber is never equal to requestedLineNum

– drescherjm
Nov 20 '18 at 21:41

While testing you probably should remove the rename() and remove()

– drescherjm
Nov 20 '18 at 21:42

You never closed the tempFile. so the rename("temp.txt", "questions.txt"); may not work.

– drescherjm
Nov 20 '18 at 21:42

Your code that copies the file seems to copy everything after the selected line.

– drescherjm
Nov 20 '18 at 21:45

add a comment |

-3

This is my code:

#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;

}

asked Nov 20 '18 at 20:58

Artain

This is my code:

#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;

}

c++ text-files

asked Nov 20 '18 at 20:58

Artain

asked Nov 20 '18 at 20:58

Artain

asked Nov 20 '18 at 20:58

Artain

asked Nov 20 '18 at 20:58

Artain

asked Nov 20 '18 at 20:58

Artain

closed as off-topic by πάντα ῥεῖ, Jean-François Fabre, Gert Arnold, Killzone Kid, Pearly Spencer Nov 20 '18 at 23:43

This question appears to be off-topic. The users who voted to close gave this specific reason:

"Questions seeking debugging help ("why isn't this code working?") must include the desired behavior, a specific problem or error and the shortest code necessary to reproduce it in the question itself. Questions without a clear problem statement are not useful to other readers. See: How to create a Minimal, Complete, and Verifiable example." – πάντα ῥεῖ, Jean-François Fabre, Gert Arnold, Killzone Kid, Pearly Spencer

If this question can be reworded to fit the rules in the help center, please edit the question.

closed as off-topic by πάντα ῥεῖ, Jean-François Fabre, Gert Arnold, Killzone Kid, Pearly Spencer Nov 20 '18 at 23:43

This question appears to be off-topic. The users who voted to close gave this specific reason:

"Questions seeking debugging help ("why isn't this code working?") must include the desired behavior, a specific problem or error and the shortest code necessary to reproduce it in the question itself. Questions without a clear problem statement are not useful to other readers. See: How to create a Minimal, Complete, and Verifiable example." – πάντα ῥεῖ, Jean-François Fabre, Gert Arnold, Killzone Kid, Pearly Spencer

If this question can be reworded to fit the rules in the help center, please edit the question.

Maybe lineNumber is never equal to requestedLineNum

– drescherjm
Nov 20 '18 at 21:41

While testing you probably should remove the rename() and remove()

– drescherjm
Nov 20 '18 at 21:42

You never closed the tempFile. so the rename("temp.txt", "questions.txt"); may not work.

– drescherjm
Nov 20 '18 at 21:42

Your code that copies the file seems to copy everything after the selected line.

– drescherjm
Nov 20 '18 at 21:45

add a comment |

Maybe lineNumber is never equal to requestedLineNum

– drescherjm
Nov 20 '18 at 21:41

While testing you probably should remove the rename() and remove()

– drescherjm
Nov 20 '18 at 21:42

You never closed the tempFile. so the rename("temp.txt", "questions.txt"); may not work.

– drescherjm
Nov 20 '18 at 21:42

Your code that copies the file seems to copy everything after the selected line.

– drescherjm
Nov 20 '18 at 21:45

Maybe lineNumber is never equal to requestedLineNum

– drescherjm
Nov 20 '18 at 21:41

While testing you probably should remove the rename() and remove()

– drescherjm
Nov 20 '18 at 21:42

You never closed the tempFile. so the rename("temp.txt", "questions.txt"); may not work.

– drescherjm
Nov 20 '18 at 21:42

Your code that copies the file seems to copy everything after the selected line.

– drescherjm
Nov 20 '18 at 21:45

add a comment |

1 Answer
1

active

oldest

votes

I've just finished writing the code for you, I'm going to explain it:

#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;

}

Let's list my edit:

1 - I've defined the variables out of the main function, it isn't necessary declare them at ever loop.

2 - For a endless loop use

 while(true) {}

for(;;) {}

instead of

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

3 - I've written:

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

cin >> requestedLineNum;

because who will run the program won't know what he have to do

4 - I've added:

 if(requestedLineNum==-1) break;

 else {...

to exit easily from the loop when you run the program

5 - I've added the

 << endl;

beacuse when the program wrote to the file before generated one line with all questions one after the other therefore in the next iteration it won't work anymore

6 - I've replaced this while loop because it was a duplicate with the extern one

//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;

}

with

//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++;

now:
1. it reads every line of the file questions.txt
2. if it is the selected question don't write it into TempFile but into usedQuestions.txt
3. if it isn't the selected question write it in the tempFile (after it'll be questions.txt)

I'm sorry for my English and I'm ready for any explanation.

edited Nov 21 '18 at 9:11

answered Nov 20 '18 at 23:07

zanddev

314

1

The code is beautiful, but it appears to not work. I get a usedQuestions.txt file which contains the correct questions, but I also get an empty temp.txt file with questions.txt being deleted.

– Artain
Nov 21 '18 at 15:17

I don't understand what temp.txt have to contain. I thought it was a temporary file to move the questions

– zanddev
Nov 22 '18 at 5:55

True. So at the end, it should have all the questions except the used ones. That is not the case. In fact, it's empty.

– Artain
Nov 22 '18 at 15:32

Then temp.txt will be the same of questions.txt? Maybe it is useless...

– zanddev
Nov 22 '18 at 23:05

sorry for being so late It is supposed to be the same, but without the used questions.

– Artain
Nov 30 '18 at 20:18

add a comment |

1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

I've just finished writing the code for you, I'm going to explain it:

#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;

}

Let's list my edit:

1 - I've defined the variables out of the main function, it isn't necessary declare them at ever loop.

2 - For a endless loop use

 while(true) {}

for(;;) {}

instead of

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

3 - I've written:

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

cin >> requestedLineNum;

because who will run the program won't know what he have to do

4 - I've added:

 if(requestedLineNum==-1) break;

 else {...

to exit easily from the loop when you run the program

5 - I've added the

 << endl;

beacuse when the program wrote to the file before generated one line with all questions one after the other therefore in the next iteration it won't work anymore

6 - I've replaced this while loop because it was a duplicate with the extern one

//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;

}

with

//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++;

I'm sorry for my English and I'm ready for any explanation.

edited Nov 21 '18 at 9:11

answered Nov 20 '18 at 23:07

zanddev

314

1

The code is beautiful, but it appears to not work. I get a usedQuestions.txt file which contains the correct questions, but I also get an empty temp.txt file with questions.txt being deleted.

– Artain
Nov 21 '18 at 15:17

I don't understand what temp.txt have to contain. I thought it was a temporary file to move the questions

– zanddev
Nov 22 '18 at 5:55

True. So at the end, it should have all the questions except the used ones. That is not the case. In fact, it's empty.

– Artain
Nov 22 '18 at 15:32

Then temp.txt will be the same of questions.txt? Maybe it is useless...

– zanddev
Nov 22 '18 at 23:05

sorry for being so late It is supposed to be the same, but without the used questions.

– Artain
Nov 30 '18 at 20:18

add a comment |

I've just finished writing the code for you, I'm going to explain it:

#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;

}

Let's list my edit:

1 - I've defined the variables out of the main function, it isn't necessary declare them at ever loop.

2 - For a endless loop use

 while(true) {}

for(;;) {}

instead of

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

3 - I've written:

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

cin >> requestedLineNum;

because who will run the program won't know what he have to do

4 - I've added:

 if(requestedLineNum==-1) break;

 else {...

to exit easily from the loop when you run the program

5 - I've added the

 << endl;

beacuse when the program wrote to the file before generated one line with all questions one after the other therefore in the next iteration it won't work anymore

6 - I've replaced this while loop because it was a duplicate with the extern one

//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;

}

with

//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++;

I'm sorry for my English and I'm ready for any explanation.

edited Nov 21 '18 at 9:11

answered Nov 20 '18 at 23:07

zanddev

314

1

The code is beautiful, but it appears to not work. I get a usedQuestions.txt file which contains the correct questions, but I also get an empty temp.txt file with questions.txt being deleted.

– Artain
Nov 21 '18 at 15:17

I don't understand what temp.txt have to contain. I thought it was a temporary file to move the questions

– zanddev
Nov 22 '18 at 5:55

True. So at the end, it should have all the questions except the used ones. That is not the case. In fact, it's empty.

– Artain
Nov 22 '18 at 15:32

Then temp.txt will be the same of questions.txt? Maybe it is useless...

– zanddev
Nov 22 '18 at 23:05

sorry for being so late It is supposed to be the same, but without the used questions.

– Artain
Nov 30 '18 at 20:18

add a comment |

I've just finished writing the code for you, I'm going to explain it:

#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;

}

Let's list my edit:

1 - I've defined the variables out of the main function, it isn't necessary declare them at ever loop.

2 - For a endless loop use

 while(true) {}

for(;;) {}

instead of

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

3 - I've written:

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

cin >> requestedLineNum;

because who will run the program won't know what he have to do

4 - I've added:

 if(requestedLineNum==-1) break;

 else {...

to exit easily from the loop when you run the program

5 - I've added the

 << endl;

beacuse when the program wrote to the file before generated one line with all questions one after the other therefore in the next iteration it won't work anymore

6 - I've replaced this while loop because it was a duplicate with the extern one

//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;

}

with

//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++;

I'm sorry for my English and I'm ready for any explanation.

edited Nov 21 '18 at 9:11

answered Nov 20 '18 at 23:07

zanddev

314

I've just finished writing the code for you, I'm going to explain it:

#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;

}

Let's list my edit:

1 - I've defined the variables out of the main function, it isn't necessary declare them at ever loop.

2 - For a endless loop use

 while(true) {}

for(;;) {}

instead of

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

3 - I've written:

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

cin >> requestedLineNum;

because who will run the program won't know what he have to do

4 - I've added:

 if(requestedLineNum==-1) break;

 else {...

to exit easily from the loop when you run the program

5 - I've added the

 << endl;

beacuse when the program wrote to the file before generated one line with all questions one after the other therefore in the next iteration it won't work anymore

6 - I've replaced this while loop because it was a duplicate with the extern one

//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;

}

with

//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++;

I'm sorry for my English and I'm ready for any explanation.

edited Nov 21 '18 at 9:11

answered Nov 20 '18 at 23:07

zanddev

314

edited Nov 21 '18 at 9:11

answered Nov 20 '18 at 23:07

zanddev

314

answered Nov 20 '18 at 23:07

zanddev

314

answered Nov 20 '18 at 23:07

zanddev

314

1

The code is beautiful, but it appears to not work. I get a usedQuestions.txt file which contains the correct questions, but I also get an empty temp.txt file with questions.txt being deleted.

– Artain
Nov 21 '18 at 15:17

I don't understand what temp.txt have to contain. I thought it was a temporary file to move the questions

– zanddev
Nov 22 '18 at 5:55

True. So at the end, it should have all the questions except the used ones. That is not the case. In fact, it's empty.

– Artain
Nov 22 '18 at 15:32

Then temp.txt will be the same of questions.txt? Maybe it is useless...

– zanddev
Nov 22 '18 at 23:05

sorry for being so late It is supposed to be the same, but without the used questions.

– Artain
Nov 30 '18 at 20:18

add a comment |

1

The code is beautiful, but it appears to not work. I get a usedQuestions.txt file which contains the correct questions, but I also get an empty temp.txt file with questions.txt being deleted.

– Artain
Nov 21 '18 at 15:17

I don't understand what temp.txt have to contain. I thought it was a temporary file to move the questions

– zanddev
Nov 22 '18 at 5:55

True. So at the end, it should have all the questions except the used ones. That is not the case. In fact, it's empty.

– Artain
Nov 22 '18 at 15:32

Then temp.txt will be the same of questions.txt? Maybe it is useless...

– zanddev
Nov 22 '18 at 23:05

sorry for being so late It is supposed to be the same, but without the used questions.

– Artain
Nov 30 '18 at 20:18

The code is beautiful, but it appears to not work. I get a usedQuestions.txt file which contains the correct questions, but I also get an empty temp.txt file with questions.txt being deleted.

– Artain
Nov 21 '18 at 15:17

I don't understand what temp.txt have to contain. I thought it was a temporary file to move the questions

– zanddev
Nov 22 '18 at 5:55

True. So at the end, it should have all the questions except the used ones. That is not the case. In fact, it's empty.

– Artain
Nov 22 '18 at 15:32

Then temp.txt will be the same of questions.txt? Maybe it is useless...

– zanddev
Nov 22 '18 at 23:05

sorry for being so late It is supposed to be the same, but without the used questions.

– Artain
Nov 30 '18 at 20:18

add a comment |

This page is only for reference, If you need detailed information, please check here

Search This Blog

Ufyukyu