std::make_pair 与 std::pair 的构造函数的目的是什么? [英] What is the purpose of std::make_pair vs the constructor of std::pair?

问题描述

std::make_pair 的目的是什么?

为什么不直接做 std::pair(0, 'a')?

这两种方法有什么区别吗?

Is there any difference between the two methods?

推荐答案

区别在于 std::pair 需要指定两个元素的类型，而 std::make_pair 将创建一个带有传递给它的元素类型的对，而无需您告诉它.无论如何，这就是我可以从各种文档中收集到的信息.

The difference is that with std::pair you need to specify the types of both elements, whereas std::make_pair will create a pair with the type of the elements that are passed to it, without you needing to tell it. That's what I could gather from various docs anyways.

从 http://www.cplusplus.com/reference/std 中查看此示例/utility/make_pair/

pair <int,int> one;
pair <int,int> two;

one = make_pair (10,20);
two = make_pair (10.5,'A'); // ok: implicit conversion from pair<double,char>

除了它的隐式转换奖励，如果你没有使用 make_pair 你就必须这样做

Aside from the implicit conversion bonus of it, if you didn't use make_pair you'd have to do

one = pair<int,int>(10,20)

每次分配给一个，时间久了会很烦...

every time you assigned to one, which would be annoying over time...

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