Nested loop only loops 3 times instead of 710 times

[ayanda83]

I am trying to implement something that resembles a "brute string search algorithm", only that I am matching strings instead of characters. I've got two files (i.e. file A and file B), the intention is to read the first line from file A and then parse the entire file B to see if that line is contained in file B. If the line is not contained in file B, the program must move on to line number 2 in file A and the process is repeated until the end of file A.

void crossRefernce(QString input1, QString input2, QString output_file)
{
    QFile file1(input1);
    QFile file2(input2);
    QFile outputFile(output_file);
 
    if(!file1.open(QFile::ReadOnly | QFile::Text))
    {
        qDebug() << "file1 not opened";
    }
 
    if(!file2.open(QFile::ReadOnly | QFile::Text))
    {
        qDebug() << "file2 not opened";
    }
 
    if(!outputFile.open(QFile::WriteOnly | QFile::Text))
    {
        qDebug() << "output file not opened";
    }
 
 
     QTextStream in_file1(&file1);
     QTextStream in_file2(&file2);
     QTextStream out(&outputFile);
 
 
     while(!in_file1.atEnd())
     {
 
        qDebug() << "Looping" <<endl;
        QString file1_str = in_file1.readLine(0);
        QString temp_file1_str =  file1_str.mid(0, file1_str.indexOf('.'));
 
            while(!in_file2.atEnd())
            {
                qDebug() << "**Inner Loop**" <<endl;
                QString file2_str = in_file2.readLine(0);
                QString temp_file2_str =  file2_str.mid(0, file2_str.indexOf('.'));
 
                if(temp_file2_str == temp_file1_str)
                {
                    qDebug() << "found" <<endl;
                    out << file2_str <<endl;
                    qDebug() << temp_file2_str <<endl;
                    file2_str.clear();
                    break;
                }
                file2_str.clear();
            }
 
 
            file1_str.clear();
        }
 
 
     file1.close();
     file2.close();
     outputFile.close();
}

void crossRefernce(QString input1, QString input2, QString output_file)
{
    QFile file1(input1);
    QFile file2(input2);
    QFile outputFile(output_file);

    if(!file1.open(QFile::ReadOnly | QFile::Text))
    {
        qDebug() << "file1 not opened";
    }

    if(!file2.open(QFile::ReadOnly | QFile::Text))
    {
        qDebug() << "file2 not opened";
    }

    if(!outputFile.open(QFile::WriteOnly | QFile::Text))
    {
        qDebug() << "output file not opened";
    }


     QTextStream in_file1(&file1);
     QTextStream in_file2(&file2);
     QTextStream out(&outputFile);


     while(!in_file1.atEnd())
     {

        qDebug() << "Looping" <<endl;
        QString file1_str = in_file1.readLine(0);
        QString temp_file1_str =  file1_str.mid(0, file1_str.indexOf('.'));

            while(!in_file2.atEnd())
            {
                qDebug() << "**Inner Loop**" <<endl;
                QString file2_str = in_file2.readLine(0);
                QString temp_file2_str =  file2_str.mid(0, file2_str.indexOf('.'));

                if(temp_file2_str == temp_file1_str)
                {
                    qDebug() << "found" <<endl;
                    out << file2_str <<endl;
                    qDebug() << temp_file2_str <<endl;
                    file2_str.clear();
                    break;
                }
                file2_str.clear();
            }


            file1_str.clear();
        }


     file1.close();
     file2.close();
     outputFile.close();
}

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My problem is that, the output of the above code indicates that the inner while loop iterates only 3 times and never executes again. The ultimate goal is to delete similar entries in file A and B and leave unique values. Your help will be greatly appreciated.

[jefftee]

Did you hit a match on the 3rd time through the inner loop? Do you really want to stop searching the rest of file2 when you find a match? Your break statement on line 47 will fall out of that inner loop. Also, when file2 is at EOF, you don't do anything to reset it, so next time through your outer loop, the inner loop won't execute. See QTextSteam::seek() to reset the file at the beginning once you fall out of the inner loop.