vector :: begin（）和std :: begin（） [英] Difference between vector::begin() and std::begin()

问题描述

在c ++中迭代一个向量，我注意到在标准库中有一个 begin（）函数，还有一个 begin 作为向量类的成员函数。

While iterating over a vector in c++, I noticed there is a begin() function in the standard library, and also a begin() as a member function of the vector class. What, if any, is the difference between the two, and which should be used over the other?

例如：

vector<int> numbers;
//Code to put values in my vector
for (vector<int>::iterator i = numbers.begin(); i < numbers.end(); i++)
    cout << *i << '\n';

vs：

vector<int> numbers;
//Code to put values in my vector
for (vector<int>::iterator i = std::begin(numbers); i < std::end(numbers); i++)
    cout << *i << '\n';

推荐答案

std :: begin ）在C ++ 11中添加，以便更容易编写通用代码（例如在模板中）。最明显的原因是，简单的C风格数组没有方法，因此没有 .begin（）。所以你可以用C型数组使用 std :: begin（），以及有自己的 begin（）和 end（）。

std::begin() was added in C++11 to make it easier to write generic code (e.g. in templates). The most obvious reason for it is that plain C-style arrays do not have methods, hence no .begin(). So you can use std::begin() with C-style arrays, as well as STL-style containers having their own begin() and end().

如果你编写的代码不是模板，你可以忽略 std :: begin（）;你的同事程序员可能会发现奇怪，如果你突然开始使用它，无处不在只是因为它是新的。

If you're writing code which is not a template, you can ignore std::begin(); your fellow programmers would probably find it odd if you suddenly started using it everywhere just because it's new.

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