C ++ std :: vector emplace vs insert [英] C++ std::vector emplace vs insert

问题描述

我想知道两者之间有什么区别。我注意到emplace是c ++ 11添加。那么为什么添加？

I was wondering what are the differences between the two. I notice that emplace is c++11 addition. So why the addition ?

推荐答案

Emplace接受必要的参数来构造一个对象，一个对象。

Emplace takes the arguments necessary to construct an object in place, whereas insert takes (a reference to) an object.

struct Foo
{
  Foo(int n, double x);
};

std::vector<Foo> v;
v.emplace(someIterator, 42, 3.1416);
v.insert(someIterator, Foo(42, 3.1416));

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