[Effective-cpp] Item 1: Uses and Abuses of vector

[Adrian Fagg]

> -----Original Message-----
> From: effective-cpp-bounces at accu.org
> [mailto:effective-cpp-bounces at accu.org]On Behalf Of Klitos Kyriacou

> Solution 1, const iterator outside the loop:
> const vector<int>::const_iterator end = vint.begin();
> for (vector<int>::const_iterator it = vint.begin(); it != end; ++it)
> 
> Solution 2, non-const iterator inside the loop:
> for (vector<int>::const_iterator it = vint.begin(), end = 
> vint.end(); it
> != end; ++it)
> 
> I don't like solution 1 because the iterator 'end' has too large a
> scope. I only want it to be accessible up to the end of the 
> loop, not to
> the end of the enclosing block.

Surely not the enclosing scope?
It does have too much scope though, being available in the loop body.

> Other languages (I think Fortran is 
> one of them)
> solve this problem by having the language specification say that the
> compiler calculates the step and end values just once at the start of
> the loop and uses a saved copy of the values in each iteration.

Pascal does that as well.
The trouble is that C++ for loops are essentially while loops in different
clothes, which is another argument in favour of for_each etc. in my view.

Regards,

Adrian

Work: mailto:adrianf at evaluategroup.com
Home: mailto:adrian.fagg at ntlworld.com

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