std::vector<int> testVector;
int iCapacity = testVector.capacity(); //returns 0
testVector.push_back(5);
iCapacity = testVector.capacity(); //returns 1
testVector.resize(10);
iCapacity = testVector.capacity(); //returns 10
testVector.pop_back();
iCapacity = testVector.capacity(); //returns 10
testVector.erase(testVector.begin(), testVector.end());
iCapacity = testVector.capacity(); //returns 10
testVector.resize(10);
iCapacity = testVector.capacity(); //returns 10
testVector.clear();
iCapacity = testVector.capacity(); //RETURNS 0!!!!!
std::vector clear zeroing capacity
Author
Hi All,
Have searched this, with no luck.
I was under the impression that, having filled my vector with objects, i could .clear() it and the underlying capacity should not be changed? I have searched some online vector resources, and almost all of them report that
.clear() simply calls .erase(begin(), end()), however, I have done a test and this is not the case. Is my version of the STL (default that is installed with vc7.1) not conforming, or is this expected behaviour?
Alex
The test I performed is below
Author
Thanks for the info.
Any idea whether this is the correct behaviour, or is my implementation of the STL buggy?
Nice game by the way.
Alex
Any idea whether this is the correct behaviour, or is my implementation of the STL buggy?
Nice game by the way.
Alex
I don't know if it's wrong, but it isn't something I would have expected.
libstdc++ and stlport both give me 10 if you wanted something to compare with it to.
libstdc++ and stlport both give me 10 if you wanted something to compare with it to.
Quote:Original post by deathkrush
I get the same behaviour with Visual Studio .NET 2003.
Indeed you do, since that is 7.1.
In VC2005, however, the last call to vector::capacity() returns 10 (which is what I and I am sure many would expect), so it must be something with previous implementations. The standard draft of 1998 (and the working draft of 2005) makes no mention (as far as I can tell) regarding capacity after a call to clear(), the only requirements being that it is equivalent to erase( begin(), end() ) and post size() == 0, so capacity could be 0, I guess.
[edit] For those who are interested, I believe the correct way to ensure a capacity of 0 is the empty-temporary/swap idiom:
std::vector< int > v;
// ...
std::vector< int >().swap( v );
jfl.
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