Sorting

From qtnode

The header file <QtAlgorithms> offers a variety of useful template-based sorting functions. These functions can take iterators onto any Qt container class and sort it in place.

One of the more powerful features of the <QtAlgorithms> sorting functions is the ability to sort according to a user-specified callback function. Qt offers a templated qGreater function for reverse sorting and a caseInsensitiveLessThan for sorting strings in a case-insensitive manner. Qt does not, however, offer a large variety of these functions, so for many sorting tasks, a custom lessThan function must be written.

Sorting strings with embedded numbers

bool numericAwareLessThan(const QString& l, const QString& r) {
    int len = l.length() < r.length() ? l.length() : r.length();
    QString ls = l, rs = r;
    QChar li, ri;
    for(int i=0; i<len; i++) {
        li = l.at(i);
        ri = r.at(i);
        if(li.isDigit() && ri.isDigit()) {
            ls = l.mid(i);
            rs = r.mid(i);
            break;
        } else {
            if(li != ri) break;
        }
    }

    double ld = ls.toDouble(), rd = rs.toDouble();
    if(ld != rd)
        return ld < rd;
    else
        return ls.localeAwareCompare(rs) < 0;
}