其他的回答都很好，我不想重复他们说过的话。

One other aspect to "why enable warnings" that hasn't properly been touched on is that they help enormously with code maintenance. When you write a program of significant size, it becomes impossible to keep the whole thing in your head at once. You typically have a function or three that you're actively writing and thinking about, and perhaps a file or three on your screen that you can refer to, but the bulk of the program exists in the background somewhere and you have to trust that it keeps working.

如果你改变的某些东西给你看不见的东西带来了麻烦，你就会提醒自己。

例如Clang警告-Wswitch-enum。如果您在枚举上使用开关而漏掉了一个可能的枚举值，则会触发警告。您可能认为这是一个不太可能犯的错误:在编写switch语句时，您可能至少查看了枚举值列表。您甚至可能有一个IDE为您生成开关选项，不为人为错误留下任何空间。

六个月后，当您向枚举中添加另一个可能的条目时，这个警告才真正发挥作用。同样，如果您正在考虑所讨论的代码，那么您可能不会有问题。但是如果这个枚举用于多个不同的目的，并且它是用于您需要额外选项的其中一个目的，那么很容易忘记更新您六个月没有接触过的文件中的开关。

You can think of warnings in the same way as you'd think of automated test cases: they help you make sure that the code is sensible and doing what you need when you first write it, but they help even more to make sure that it keeps doing what you need while you prod at it. The difference is that test cases work very narrowly to the requirements of your code and you have to write them, while warnings work broadly to sensible standards for almost all code, and they're very generously supplied by the boffins who make the compilers.

众所周知，就hll而言，C是一种相当低级的语言。虽然c++看起来是一种比C高级得多的语言，但它仍然具有C的一些特征。其中一个特点就是这些语言是由程序员设计的，为程序员设计的——特别是那些知道自己在做什么的程序员。

(对于这个答案的其余部分，我将专注于C。我要说的大部分内容也适用于c++，尽管可能没有那么强烈。尽管Bjarne Stroustrup有一句名言:“C很容易搬起石头砸自己的脚;c++让它变得更难，但当你这样做的时候，它会把你的整条腿都炸掉。”)

如果你知道你在做什么——真的知道你在做什么——有时候你可能不得不“打破规则”。但大多数时候，我们大多数人都会同意，善意的规则让我们所有人都远离麻烦，一直肆意违反这些规则是一个坏主意。

But in C and C++, there are surprisingly large numbers of things you can do that are "bad ideas", but which aren't formally "against the rules". Sometimes they're a bad idea some of the time (but might be defensible other times); sometimes they're a bad idea virtually all of the time. But the tradition has always been not to warn about these things — because, again, the assumption is that programmers know what they are doing, they wouldn't be doing these things without a good reason, and they'd be annoyed by a bunch of unnecessary warnings.

当然，并不是所有的程序员都知道自己在做什么。特别是，每个C程序员(无论多么有经验)都要经历一个开始C程序员的阶段。即使是有经验的C程序员也会粗心大意，犯错误。

最后，经验表明，程序员不仅会犯错误，而且这些错误会产生真正的、严重的后果。如果你犯了一个错误，编译器没有警告你，而且程序没有立即崩溃，或者因为它而做一些明显的错误，这个错误可能潜伏在那里，隐藏，有时长达数年，直到它造成一个真正的大问题。

So it turns out that, most of the time, warnings are a good idea, after all. Even the experienced programmers have learned that (actually, it's "especially the experienced programmers have learned that"), on balance, the warnings tend to do more good than harm. For every time you did something wrong deliberately and the warning was a nuisance, there are probably at least ten times you did something wrong by accident and the warning saved you from further trouble. And most warnings can be disabled or worked around for those few times when you really want to do the "wrong" thing.

(这类“错误”的一个经典例子是if(A = b)的测试。大多数时候，这确实是一个错误，所以现在大多数编译器都会对此发出警告——有些甚至是默认的。但是如果你真的想把b赋值给a并测试结果，你可以通过输入if((a = b))来禁用警告。

The second question is, why would you want to ask the compiler to treat warnings as errors? I'd say it's because of human nature, specifically, the all-too-easy reaction of saying "Oh, that's just a warning, that's not so important, I'll clean that up later." But if you're a procrastinator (and I don't know about you, but I'm a world-class procrastinator) it's easy to put off the necessary cleanup for basically ever — and if you get into the habit of ignoring warnings, it gets easier and easier to miss an important warning message that's sitting there, unnoticed, in the midst of all the ones you're relentlessly ignoring.

因此，要求编译器将警告视为错误是你可以对自己玩的一个小技巧，以避免这个人类的弱点，迫使自己立即修复警告，否则你的程序将无法编译。

Personally, I'm not as insistent about treating warnings as errors — in fact, if I'm honest, I can say that I don't tend to enable that option in my "personal" programming. But you can be sure I've got that option enabled at work, where our style guide (which I wrote) mandates its use. And I would say — I suspect most professional programmers would say — that any shop that doesn't treat warnings as errors in C is behaving irresponsibly, is not adhering to commonly-accepted industry best practices.

由于某些原因，c++中的编译器警告非常有用。

它可以告诉你，你可能在哪里犯了一个错误，这可能会影响你的操作的最终结果。例如，如果你没有初始化一个变量，或者如果你使用“=”而不是“==”(这只是例子) 它还允许向你展示你的代码不符合c++标准的地方。这很有用，因为如果代码符合实际标准，那么将很容易将代码移到其他平台。

一般来说，警告是非常有用的，可以告诉您代码中哪里有错误，这些错误可能会影响算法的结果，或者在用户使用您的程序时防止出现某些错误。

忽略警告意味着您留下了草率的代码，这不仅会在将来给其他人带来问题，而且还会使您不太注意到重要的编译消息。

编译器输出越多，就越不会有人注意到。越干净越好。这也意味着你知道自己在做什么。警告是非常不专业、粗心和危险的。

别着急:你不必这么做，也没有必要。-Wall和-Werror是由代码重构狂人为自己设计的:它是由编译器开发人员发明的，目的是避免在用户端编译器或编程语言更新后破坏现有的构建。特性本身并不是什么，而是关于是否破坏构建的决定。

使用与否完全取决于您的喜好。我一直在用它，因为它能帮我改正错误。

处理警告不仅能写出更好的代码，还能让你成为更好的程序员。警告会告诉你一些今天对你来说微不足道的事情，但总有一天坏习惯会回来咬你的头。

使用正确的类型，返回该值，计算该返回值。花点时间思考“在这种情况下，这真的是正确的类型吗?”“我需要把这个还回去吗?”最重要的是;“这个代码在未来10年里还能移植吗?”

首先要养成编写无警告代码的习惯。