Iterating backward
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by MBennett
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Published on 2010-03-30T21:33:22Z
Indexed on
2010/03/30
21:43 UTC
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Suppose I have a vector<int> myvec
and I want to loop through all of the elements in reverse. I can think of a few ways of doing this:
for (vector<int>::iterator it = myvec.end() - 1; it >= myvec.begin(); --it)
{
// do stuff here
}
for (vector<int>::reverse_iterator rit = myvec.rbegin(); rit != myvec.rend(); ++rit)
{
// do stuff here
}
for (int i = myvec.size() - 1; i >= 0; --i)
{
// do stuff here
}
So my question is when should I use each? Is there a difference? I know that the first one is dangerous because if I pass in an empty vector, then myvec.end() - 1
is undefined, but are there any other hazards or inefficiencies with this?
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