Insert the value on certain line and column of text file - c++

Question

I want to insert the value of double spin box on 14th line and 19th column of my large text file. I have created loop to insert the value on 14th line, but it is just placed on first column of the line. Can anyone help me to move the value after text, parameter PW_x = ?
This is the portion of my text file.
parameter PW_x = "i want to insert value here this is 14th line and 19th column"
parameter PW_y =
parameter PD =
parameter PC =
This is my code
void MainWindow::on_doubleSpinBox_6_editingFinished()
{
QString file("D:\\my text file name");
QFile outputFile(file);
if (outputFile.open(QIODevice::ReadWrite | QIODevice::Text))
{
for (int i=0;i<13;i++) {
outputFile.readLine();
}
QTextStream stream(&outputFile);
stream << QString::number(ui->doubleSpinBox_6->value());
}
}

Answer 1

As I advised in my comment, you should parse->edit->save
you can for sure use other ways to insert the value in the file, like trying to match and replace the string in each line of the file (be aware that this is very inefficient..) but here an example:
in the for loop, try to replace the string "PW_x = " with the value PW_x = 'your spinbox double', the replace action will leave intact all the lines that dont match the string you are looking for...
here an example
QString l1{"parameter PW_x = " };
QString l2{"parameter PW_y = " };
QString l3{"parameter PD = " };
QString l4{"parameter PC = " };
QString doubleAsString{"3.1415"};
l1.replace("PW_x = ", "PW_x = " + doubleAsString);
l2.replace("PW_x = ", "PW_x = " + doubleAsString);
l3.replace("PW_x = ", "PW_x = " + doubleAsString);
l4.replace("PW_x = ", "PW_x = " + doubleAsString);
qDebug() << "v1: " << l1;
qDebug() << "v2: " << l2;
qDebug() << "v3: " << l3;
qDebug() << "v4: " << l4;