如果一个敏锐&有意地尽可能长地推迟变量定义？

本文介绍了如果一个敏锐&有意地尽可能长地推迟变量定义？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

在他的书 Effective C ++ Scott Meyers 中提出了一个有趣的指南，

In his book Effective C++ Scott Meyers brings out one interesting guideline,

项目26：尽可能地延迟变量定义。它增加程序清晰度提高程序效率。

Item 26: Postpone variable definitions as long as possible. It increases program clarity & improves program efficiency.

他提出支持上述的论点是，每当一个变量被创建或破坏，建筑& 我们可能有多个控制流，其中我们可能从函数返回，而不使用早期定义的变量（在函数的开头）&因此可能不必要地产生创建未使用的变量的成本。

The argument he puts forward to support the above is that, whenever a variable is created or destructed we incur some cost for construction & destruction of the variable. We may have multiple control flows where in we might return from the function without making use of a variable defined early(at the beginning of the function) & thus may unnecessarily incur the cost of creation of the unused variable.

这似乎是逻辑的，确实是一个好的做法。来自 c 背景我有一个趋势，在函数块的开头声明我的所有变量。也许它只是 c 背景，但我也觉得有一个函数中的一个地方的所有声明提供了方便，更好的可读性。

It all seems to be logical, & indeed a good practice. Coming from a c background I have a tendency of declaring all my variable at the beginning of a function block. Maybe it is merely the c background but I also feel having all declarations at one place in a function provides for easy & better readability.

所以问题是，你们中有多少人在日常编程中实际上遵循这样的做法，或者只是试图遵循这样的练习。

So the question is how many of you do actually follow such a practice, in day to day programming or it is merely an overkill to attempt to follow such a practice.

推荐答案

我当然会。它确实需要一些适应新的习惯（从其他语言自己我知道你的意思），但一旦你在那里，它是更方便。除了您提及的内容，我还看到了2个优点：

I certainly do. It indeed takes some adaptation to the new habit (coming from other languages myself I know what you mean), but once you're there, it's much more convenient. I see 2 more benefits in addition to what you mention:

提高可读性： 缓存在大脑中记住在函数范围中使用的变量。

improved readability: you need less "cache" in your brain to remember the variables used in the function scope. Every small peace of code defines its own variables.

初始化：这是一个非常重要的原则，可能。在函数开始时并不总是可以知道初始化值

initialization: it is a very important principle that variables should be defined initialized whenever possible. It is not always possible to know the initialization value at the beginning of a function