反向迭代的无符号循环变量 [英] Reverse iteration with an unsigned loop variable

问题描述

我已经讨论与同事利用为size_t的。已经想出一个问题是，递减循环变量，直到它达到零的循环

I've been discussing the use of size_t with colleagues. One issue that has come up is loops that decrement the loop variable until it reaches zero.

考虑以下code：

for (size_t i = n-1; i >= 0; --i) { ... }

这会导致一个无限循环，由于无符号整数环绕。你怎么在这种情况下怎么办？这似乎远易写上面的code和不知道你犯了一个错误。

This causes an infinite loop due to unsigned integer wrap-around. What do you do in this case? It seems far to easy to write the above code and not realise that you've made a mistake.

这是我们队的两个建议是使用下列方式之一：

Two suggestions from our team are to use one of the following styles:

for (size_t i = n-1; i != -1 ; --i) { ... }

for (size_t i = n; i-- > 0 ; ) { ... }

但我不知道其他的选择还有...

But I do wonder what other options there are...

推荐答案

我个人是来这样的：

for (size_t i = n; i --> 0 ;)

它有一个），没有搞笑的 1 ，B）的条件检查助记符，三）用合适的笑脸结束。

It has a) no funny -1, b) the condition check is mnemonic, c) it ends with a suitable smiley.

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