------- Comment #5 from fang at csl dot cornell dot edu 2006-11-03 07:28 ------- > There is no argument against the ISO standard, but to a non C/C++ programmer > it seems a waist of time to reallocate the array and initialize it when one > wants to add something to an array. Some other compilers will copy the > existing data into the newly allocated space which seems more in line with > the text book. > The application will be changed to avoid the loss of data on a resize of > arrays, which is a better idea anyway. Thanks for the speedy reply.
If you really want efficient appending to a dynamically allocated array, then use std::vector, which is capable of pre-allocating more memory than the number of elements, using the reserve() member function. From looking in the implementation, N push_back operations result in lg N reallocations, by doubling the reserve size each time the capacity is exceeded. vector achieves this by tracking three pointers: beginning, end-of-elements (size), end-of-storage (capacity). valarray is lighter-weight, having only two pointers, beginning- and end-of-storage; thus it must reallocate upon resize (otherwise, how could size() be reported correctly?). I'd only use valarray when the sizeof(container) is crucial and/or the size of the container is unlikely/infrequently to change at run-time. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29688
