How to get the status of an URL?

Question

I am using Qt and what I should do is given a QString containing my URL, before opening the page, I want to know if this is reachable.

I read the documentation of QNetworkReply and I saw that there are different codes for the different types of error (eg: the remote content was not found at the server -> code 203).

The question is: starting from my QString, how can I get those code values?

Answer 1

How to know if this is reachable, before opening the page?

It is not something you could know in advance, but a trial and error:

1. Make the request
2. Check for errors
3. Get the error code

How can I do this?

Let's take the example from the documentation:

QNetworkAccessManager *manager = new QNetworkAccessManager(this);
QNetworkRequest request;

request.setUrl(QUrl("http://put.your-url.here"));

QNetworkReply *reply = manager->get(request);

connect(reply, &QIODevice::readyRead, this, &MyClass::slotReadyRead);
connect(reply, &QNetworkReply::errorOccurred,
        this, &MyClass::slotError);
connect(reply, &QNetworkReply::sslErrors,
        this, &MyClass::slotSslErrors);

Now in the implementation of MyClass::slotError, write:

qDebug() << static_cast<QNetworkReply *>(sender())->error();

This should print the error code, if any.