What is difference between "for(vector::iterator it=a.begin();it!=a.end();it++)" and "for(vector::iterator it=a.begin();it!=a.end();++it)"

Question

sometimes I see

for(vector<int>::iterator it=a.begin();it!=a.end();it++){
}

and sometimes

for(vector<int>::iterator it=a.begin();it!=a.end();++it){
}

It seems no difference when I try to print some vector to test, but not sure if it has some difference in side effect, is there any difference between them?

If you were to print each (it). The first It++ would show the value then increment and ++it would increment then show value. It does matter in some cases — Dan Beaulieu, May 19 '15 at 04:16

score 1 · Answer 1 · answered May 19 '15 at 04:16

In your question you copied the same code, however the title indicates your confusion lies in pre-increment (++it) vs. post-increment (it++). There actually is an important difference here: The pre-increment operator will increment it and return the incremented value. The post-increment operator will also increment it but will return the old value. The same logic applies to the pre and post decrement operators (--it) and (it--).

However, in a for loop, the behavior will be the same regardless of which (pre or post) you use.

What is difference between "for(vector::iterator it=a.begin();it!=a.end();it++)" and "for(vector::iterator it=a.begin();it!=a.end();++it)"

1 Answers1