Re: Memory leak on small stl vectors

From:
Francis Glassborow <francis@robinton.demon.co.uk>
Newsgroups:
comp.lang.c++.moderated
Date:
1 Jul 2006 13:55:24 -0400
Message-ID:
<OZAMYrpLYlpEFwy1@robinton.demon.co.uk>
In article <1151711252.217711.143700@b68g2000cwa.googlegroups.com>,
dr_num <hj000vi@vug.uni-duisburg.de> writes

   vector<size_t> vp;
   for(size_t iii = 0; iii<3; iii++) {
       vp.push_back(iii);
   };
   vector<size_t>* tvp;
   tvp = new vector<size_t>[1000000];
// copy
   for(size_t i = 0; i<1000000; i++) {
       tvp[i] = vp;
   };
// clear
   for(size_t i = 0; i<1000000; i++) {
       tvp[i].clear();
   };
// delete
   delete [] tvp;


Rather than try to get my mind round such complexity (I hate high level
use of the new expression as it almost always leads to problems. If
nothing else you have a problem with exception safety. Consider

typedef std::vector<unsigned int> vs_t;
// note that I am deeply suspicious of your use
// of size_t in this context but note that my
// change can be changed back by a single
// change to my code
vs_t vp(3);
for(int i(0); i != 3; ++i){
   vp[i] = i;
}
std::vector<vs_t> tvp(1000000, vp);

// tvp will be cleaned up when it goes out of scope
// including when an exception is thrown through
// the code block between the point of definition and
// the end of the block.

--
Francis Glassborow ACCU
Author of 'You Can Do It!' and "You Can Program in C++"
see http://www.spellen.org/youcandoit
For project ideas and contributions: http://www.spellen.org/youcandoit/projects

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