是否可以使用std :: for_each来突变对象？ [英] Is it ok to mutate objects with std::for_each?

问题描述

for_each接受InputIterators：

for_each accepts InputIterators :

//from c++ standard
template <class InputIterator, class Function>
   Function for_each (InputIterator first, InputIterator last, Function f);

可以更改Function f中的对象，如下所示：

is it ok to change the object in Function f, like this :

struct AddOne
{
    void operator()(int & x){x = x + 1;}
};

std::vector<int> vec(10);
std::for_each(vec.begin(),vec.end(),AddOne());

此代码适用于VC ++ 2008以及GCC，代码？

（InputIterators只能保证可用作右值，在这种情况下，它们在AddOne的operator（）中用作左值）

This code works in VC++2008 and also with GCC, but is it also portable (legal) code ?
(InputIterators are only guaranteed to be usable as rvalue, in this case they are used as lvalue in AddOne's operator())

推荐答案

阅读此文章。

要小心： for_each 是非修改序列操作。目的不是修改序列。但是，使用 for_each 时可以修改输入序列。

To be pedantic: for_each is a non-modifying sequence operation. The intent is not to modify the sequence. However, it is okay to modify the input sequence when using for_each.

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