The example for QByteArray::lastIndexOf() contains:

QByteArray x("crazy azimuths"); 
QByteArray y("azy"); 
x.lastIndexOf(y); // returns 6 
x.lastIndexOf(y, 6); // returns 6 
x.lastIndexOf(y, 5); // returns 2 
x.lastIndexOf(y, 1); // returns -1 

But it is definitely wrong, since there's only one "azy" substring in the string. The other is "azi", not "azy".

Note that this problem was fixed in QString::lastIndexOf(), but was apparently forgotten for QByteArray.