使用“for"循环遍历 C++ 向量

问题描述

我是 C++ 语言的新手.我已经开始使用向量，并注意到在我看到的所有通过索引迭代向量的代码中，for 循环的第一个参数总是基于向量的东西.在 Java 中，我可能会用 ArrayList 做这样的事情:

I am new to the C++ language. I have been starting to use vectors, and have noticed that in all of the code I see to iterate though a vector via indices, the first parameter of the for loop is always something based on the vector. In Java I might do something like this with an ArrayList:

for(int i=0; i < vector.size(); i++){
   vector[i].doSomething();
}

有什么原因我在 C++ 中看不到这个吗?这是不好的做法吗?

Is there a reason I don't see this in C++? Is it bad practice?

推荐答案

有什么原因我在 C++ 中看不到这个吗?这是不好的做法吗?

没有.这不是一个坏习惯，但以下方法使您的代码具有一定的灵活性.

No. It is not a bad practice, but the following approach renders your code certain flexibility.

通常，在 C++11 之前，迭代容器元素的代码使用迭代器，例如:

Usually, pre-C++11 the code for iterating over container elements uses iterators, something like:

std::vector<int>::iterator it = vector.begin();

这是因为它使代码更加灵活.

This is because it makes the code more flexible.

所有标准库容器都支持并提供迭代器.如果在以后的开发中需要切换到另一个容器，则不需要更改此代码.

All standard library containers support and provide iterators. If at a later point of development you need to switch to another container, then this code does not need to be changed.

注意:编写适用于所有可能的标准库容器的代码并不像看起来那么容易.

Note: Writing code which works with every possible standard library container is not as easy as it might seem to be.

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