问题
Looking through the C++ vector documents, pop_back() is a function that will not cause a reallocation of the vector's data. However, this only works for removing one member of the vector. I am trying to find a way to erase multiple members from the end of a vector. Originally I thought I would call pop_back() in a small for loop but I was wandering if there was a more convenient function that would do this for me?
Edit: The Cplusplus vector erase() reference is not as clear as it should be as pointed out by juanchopanza. It is why I originally discarded using erase(). Erase afterall, works well.
回答1:
Use vector::erase. It will not reallocate memory.
If your erased range does not extend to the end of the container, it WILL re-locate the end elements. That means the ending elements will be moved to their proper spot in memory which likely incurs a data copy. That is not the same as a re-allocation of the backing store. If your ending element is myVector.end(), no relocation will need to occur.
回答2:
You can use member functions erase. The vector will not be reallocated because according to the C++ Standard, e.g. C++17 n4659 standard draft 26.3.11.5 [vector.modifiers] "vector modifiers":
iterator erase(const_iterator position); iterator erase(const_iterator first, const_iterator last);3 Effects: Invalidates iterators and references at or after the point of the erase.
The bold part of the quote means that the vector will not be reallocated.
来源：https://stackoverflow.com/questions/25004618/c-erasing-part-of-the-end-of-a-vector-without-reallocation