- **C++**
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- - **clear() vs destructor?**
(*http://www.velocityreviews.com/forums/t632751-clear-vs-destructor.html*)

clear() vs destructor?For a std::vector, what's the difference between
the clear() function and its destructor? I know their usages are different, but how about their implementations? |

Re: clear() vs destructor?On Aug 28, 2:24*pm, Lambda <stephenh...@gmail.com> wrote:
> For a std::vector, what's the difference between > the clear() function and its destructor? > > I know their usages are different, > but how about their implementations? clear is to clear the data but not the memory allocation. destructor clears everything. |

Re: clear() vs destructor?On Aug 28, 9:37*pm, "C C++ C++" <m.azm...@gmail.com> wrote:
> On Aug 28, 2:24*pm, Lambda <stephenh...@gmail.com> wrote: > > > For a std::vector, what's the difference between > > the clear() function and its destructor? > > > I know their usages are different, > > but how about their implementations? > > clear is to clear the data but not the memory allocation. > destructor clears everything. Do you mean: 1. If the vector has 100 elements 2. clear() 3. Then the 100 memory spaces are not released, and all the 100 elements are uninitialized? |

Re: clear() vs destructor?On Aug 28, 2:47*pm, Lambda <stephenh...@gmail.com> wrote:
> On Aug 28, 9:37*pm, "C C++ C++" <m.azm...@gmail.com> wrote: > > > On Aug 28, 2:24*pm, Lambda <stephenh...@gmail.com> wrote: > > > > For a std::vector, what's the difference between > > > the clear() function and its destructor? > > > > I know their usages are different, > > > but how about their implementations? > > > clear is to clear the data but not the memory allocation. > > destructor clears everything. > > Do you mean: > 1. If the vector has 100 elements > 2. clear() > 3. Then the 100 memory spaces are not released, and > all the 100 elements are uninitialized? It will release all 100 but keep the minimum memory space required for vector. |

Re: clear() vs destructor?On Aug 28, 2:47*pm, Lambda <stephenh...@gmail.com> wrote:
> On Aug 28, 9:37*pm, "C C++ C++" <m.azm...@gmail.com> wrote: > > > On Aug 28, 2:24*pm, Lambda <stephenh...@gmail.com> wrote: > > > > For a std::vector, what's the difference between > > > the clear() function and its destructor? > > > > I know their usages are different, > > > but how about their implementations? > > > clear is to clear the data but not the memory allocation. > > destructor clears everything. > > Do you mean: > 1. If the vector has 100 elements > 2. clear() > 3. Then the 100 memory spaces are not released, and > all the 100 elements are uninitialized? "Calling clear() removes all elements from the controlled sequence. The memory allocated is not freed, however. All iterators become invalid, of course." - from codeguru dot com c++ article number c4027 |

Re: clear() vs destructor?On Aug 28, 12:48*pm, ytrem...@nyx.nyx.net (Yannick Tremblay) wrote:
> In article <4b923fa1-75a4-45e0-b385-3674aecd0...@k30g2000hse.googlegroups..com>, > C C++ C++ <m.azm...@gmail.com> wrote: > Not sure what the standard says but my implementation does not release > any memory. *I am pretty sure it is not required by the satandard to > release the memory. *I don't know if it is allowed but I don't think I > have noticed an implementation that shrink the vector capacity. *Each > elements of the vector will however be destructed correctly when > clear() is called. In fact, the opposite is true. It is "required" that memory not be released. (in so far at least that the capacity() of the vector before and after a clear() will remain the same) Joe Cook |

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