[SOLVED] QList::operator<< or QList::append()?
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Greetings.
Similar to my previous post, now I'm undecided about which is more convenient to use to add items to a constant QList (more precisely, a const QList< cv::Mat >& ):
(1) QList::operator <<
or
(2) QList::append()
In both cases, considering the version that adds only one element at a time.
Do they have the same performance? or one is better than the other?
Thanks in advance for any help and/or suggestions.
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You can also use QList::operator+= :-)
I think they are all the same, choose the one you like best. You can, of course, ask Thiago (the maintainer of QtCore) about this, he may know a lot about performance considerations, but I doubt this is really that important. Remember the famous quote about premature optimisation ;-)
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Thank you.
As in my previous post, I guess that being a constant QList, the various options will have a similar performance. However, no hurts to ask.
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In the QList header file you'll find:
@inline QList<T> &operator+=(const T &t) {
append(t); return *this;
}
inline QList<T> &operator<< (const T &t) {
append(t); return *this;
}@So using append() directly saves one indirection, but due to the inlining I'd doubt it makes a real difference on performance.
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When adding multiple elements, using << has the advantage you can do:
@myList << a << b << c << d;@Probably not faster than multiple append()'s, but clearer code ;-)
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Thanks for the information MuldeR, now the matter is clarified.
