Qt does not display a specific line from a txt file-CodePudding

Hello everyone here is my concern, it concerns c with Qt:

Part of my project is to go display a random line from a txt file containing names, I made a first program that does that and it works perfectly, here it is (here the random number is defined).

std::ifstream file("noms.txt");
std::string line;
std::string response_string = "452";
int randomLine = std::stoi(response_string);
for (int i = 0; i <= randomLine; i  ) {
  std::getline(file, line);}

std::cout << line;

but when i implement this code when my program complete (here is the relevant part)

std::ifstream file("noms.txt");
std::string line;
int randomLine = std::stoi(response_string);
for (int i = 0; i <= randomLine; i  ) {
     std::getline(file, line);}

QString qstringLine = QString::fromStdString(line);
nom->setText(qstringLine);

Here, when I put some value in the label "name", it is displayed, but when I put the line of the txt, it does not work (Here, the response_string variable is a character (but a number) coming from an api)

Have-you any idea ?

I have already tried not to convert the line to QString, I have already tried to display only the result of the api (it works), I think the problem is between reading the line and the display. I also tried to update the widget.

CodePudding user response：

QTextStream class and QTextStream::readLine() function can do it better. Example:

QFile data("noms.txt");
const auto line_num{200};
QString line;
if (data.open(QIODevice::ReadOnly | QIODevice::Text)) {
    QTextStream stream(&data); 
    for (auto i{0}; i < line_num && stream.readLineInto(&line);   i) {}
}

qDebug() << "line num 200:" << line;

CodePudding user response：

I close this post, thank you for your help but I found (a problem of path and access permissions).