c ++ std :: list sort保留顺序

Question

可能重复:
std :: list <> :: sort stable？

C++ std :: list sort函数是否保证保留列表中相等元素的顺序？例如,如果我们在列表中有对象A,B和C并且比较运算符被重载,那么A == C和B <A,我们是否必须获得BAC或者是否可以获得BCA？

Answer 1

是的,在C++中list::sort()是稳定的,符合ISO 14882:2003 23.2.2.4 [lib.list.ops]/31

Effects: Sorts the list according to the operator< or a Compare function object.
Notes: Stable: the relative order of the equivalent elements is preserved. 
If an exception is thrown the order of the elements in the list is indeterminate.

Answer 2

是的,标准要求list :: sort保持稳定.