Negative regexp

[mero]

Hello,

I have problem with negative regexp in QT,
I've want capture string after "//"
example: in "//aaa" - i want "aaa"
but I dont want capture when before "//" is http: or https:

I've tried this 4 regexp, but all are wrong ...

please help

#include <QCoreApplication>
#include <QRegExp>
#include <QDebug>
 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
    QRegExp rx1("(ftp:|http:|https:){0}//([a-zA-Z0-9_-]+)");
    QRegExp rx2("[^(ftp:|http:|https:)]//([a-zA-Z0-9_-]+)");
    QRegExp rx3("(?=(ftp:|http:|https:))//([a-zA-Z0-9_-]+)");
    QRegExp rx4("(?!(ftp:|http:|https:))//([a-zA-Z0-9_-]+)");
 
    QString strData;
    strData = "//aaa";
 
    // should be != -1
    qDebug() << "1:" << rx1.indexIn(strData) << " " << (rx1.indexIn(strData) != -1 ? "OK" : "WRONG");
    qDebug() << "2:" << rx2.indexIn(strData) << " " << (rx2.indexIn(strData) != -1 ? "OK" : "WRONG");
    qDebug() << "3:" << rx3.indexIn(strData) << " " << (rx3.indexIn(strData) != -1 ? "OK" : "WRONG");
    qDebug() << "4:" << rx4.indexIn(strData) << " " << (rx4.indexIn(strData) != -1 ? "OK" : "WRONG");
 
    qDebug() << "";
    strData = "http://aaa";
 
    // should be == -1
    qDebug() << "1:" << rx1.indexIn(strData) << " " << (rx1.indexIn(strData) == -1 ? "OK" : "WRONG");
    qDebug() << "2:" << rx2.indexIn(strData) << " " << (rx2.indexIn(strData) == -1 ? "OK" : "WRONG");
    qDebug() << "3:" << rx3.indexIn(strData) << " " << (rx3.indexIn(strData) == -1 ? "OK" : "WRONG");
    qDebug() << "4:" << rx4.indexIn(strData) << " " << (rx4.indexIn(strData) == -1 ? "OK" : "WRONG");
 
// rx.cap ... etc
 
    return a.exec();
}

#include <QCoreApplication>
#include <QRegExp>
#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QRegExp rx1("(ftp:|http:|https:){0}//([a-zA-Z0-9_-]+)");
    QRegExp rx2("[^(ftp:|http:|https:)]//([a-zA-Z0-9_-]+)");
    QRegExp rx3("(?=(ftp:|http:|https:))//([a-zA-Z0-9_-]+)");
    QRegExp rx4("(?!(ftp:|http:|https:))//([a-zA-Z0-9_-]+)");

    QString strData;
    strData = "//aaa";

    // should be != -1
    qDebug() << "1:" << rx1.indexIn(strData) << " " << (rx1.indexIn(strData) != -1 ? "OK" : "WRONG");
    qDebug() << "2:" << rx2.indexIn(strData) << " " << (rx2.indexIn(strData) != -1 ? "OK" : "WRONG");
    qDebug() << "3:" << rx3.indexIn(strData) << " " << (rx3.indexIn(strData) != -1 ? "OK" : "WRONG");
    qDebug() << "4:" << rx4.indexIn(strData) << " " << (rx4.indexIn(strData) != -1 ? "OK" : "WRONG");

    qDebug() << "";
    strData = "http://aaa";

    // should be == -1
    qDebug() << "1:" << rx1.indexIn(strData) << " " << (rx1.indexIn(strData) == -1 ? "OK" : "WRONG");
    qDebug() << "2:" << rx2.indexIn(strData) << " " << (rx2.indexIn(strData) == -1 ? "OK" : "WRONG");
    qDebug() << "3:" << rx3.indexIn(strData) << " " << (rx3.indexIn(strData) == -1 ? "OK" : "WRONG");
    qDebug() << "4:" << rx4.indexIn(strData) << " " << (rx4.indexIn(strData) == -1 ? "OK" : "WRONG");

// rx.cap ... etc

    return a.exec();
}

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[maximebd]

?! is the negative lookahead operator, it doesn't work for stuff before. What you can do is to have a non-capturing group to define a group that starts the line with ^https?://.*

I haven't tested it, but it should look like:

QRegExp rx("(?:^(?:ftp|http|https)://.*$)?//(\\w+)");

QRegExp rx("(?:^(?:ftp|http|https)://.*$)?//(\\w+)");

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I am not sure of the usage of a non-capturing group within a non-capturing group. You might need to use (?:ftp://.*|http://.*|https://.*) instead.

- Maxime