C++ Programming :: allocator.destroy()


	allocator.destroy() Why does the value of the below int pointer not disappear after using destroy: std::allocator<int> allo; int* ip; allo.construct(ip,777); std::cout << "ip = " << ip << std::endl; allo.destroy(ip); std::cout << "ip = " << ip << std::endl; I get two prints with 777. - Hide quoted text - desktop wrote: > Why does the value of the below int pointer not disappear after using > destroy: > std::allocator<int> allo; > int* ip; > allo.construct(ip,777); > std::cout << "ip = " << ip << std::endl; > allo.destroy(ip); > std::cout << "ip = " << ip << std::endl; > I get two prints with 777. What do you think "destroy" does ? What do you expect it to do ? It's undefined in this case. It might print 777 on your platform, it might not on mine and it might melt the cpu on other platforms. On 4 Juni, 23:14, Gianni Mariani <gi3nos@mariani.ws> wrote: - Hide quoted text - > desktop wrote: > > Why does the value of the below int pointer not disappear after using > > destroy: > > std::allocator<int> allo; > > int* ip; > > allo.construct(ip,777); > > std::cout << "ip = " << ip << std::endl; > > allo.destroy(ip); > > std::cout << "ip = " << ip << std::endl; > > I get two prints with 777. > What do you think "destroy" does ? What do you expect it to do ? > It's undefined in this case. It might print 777 on your platform, it > might not on mine and it might melt the cpu on other platforms. Did I read you post wrong? Because to me it seems like the call to destroy is quite defined while the last line (where the pointer is dereferenced) is undefined. -- Erik Wikstrm - Hide quoted text - Erik Wikstrm wrote: > On 4 Juni, 23:14, Gianni Mariani <gi3nos@mariani.ws> wrote: >> desktop wrote: >>> Why does the value of the below int pointer not disappear after using >>> destroy: >>> std::allocator<int> allo; >>> int* ip; >>> allo.construct(ip,777); >>> std::cout << "ip = " << ip << std::endl; >>> allo.destroy(ip); >>> std::cout << "ip = " << ip << std::endl; >>> I get two prints with 777. >> What do you think "destroy" does ? What do you expect it to do ? >> It's undefined in this case. It might print 777 on your platform, it >> might not on mine and it might melt the cpu on other platforms. > Did I read you post wrong? The second sentence refers to the code in the post - in particular the second *ip. > ... Because to me it seems like the call to > destroy is quite defined while the last line (where the pointer is > dereferenced) is undefined. Yeah - it may be stated in an ambiguous way.