Comparing "const char*" and QString with operator "<", ">", "<=" and ">=" gives wrong results. The inline functions in "qstring.h" from line 1043 till 1050 make terrible mistakes:

inline QT_ASCII_CAST_WARN bool operator<(const char *s1, const QString &s2)

{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) < 0; }

inline QT_ASCII_CAST_WARN bool operator>(const char *s1, const QString &s2)

{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) > 0; }

inline QT_ASCII_CAST_WARN bool operator<=(const char *s1, const QString &s2)

{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) <= 0; }

inline QT_ASCII_CAST_WARN bool operator>=(const char *s1, const QString &s2)

{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) >= 0; }

Also in line 1374 till 1381:
inline QT_ASCII_CAST_WARN bool operator<(const char *s1, const QStringRef &s2)

{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) < 0; }

inline QT_ASCII_CAST_WARN bool operator<=(const char *s1, const QStringRef &s2)

{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) > 0; }

inline QT_ASCII_CAST_WARN bool operator>(const char *s1, const QStringRef &s2)

{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) <= 0; }

inline QT_ASCII_CAST_WARN bool operator>=(const char *s1, const QStringRef &s2)

{ return QString::compare_helper(s2.constData(), s2.size(), s1, -1) >= 0; }

As you can see the arguments s1 and s2 are swap for "compare_helper" but the operators aren't swap. Also the operator "<=" returns "> 0" and ">" returns "<= 0". So "a <= a" would return false and "a > a" would return true.