每个人都知道Dijkstra的《致编辑的信》:goto语句被认为是有害的(这里。html transcript和这里。pdf)，从那时起，就有一种强大的推动力，尽可能避免使用goto语句。虽然可以使用goto来生成不可维护的、庞大的代码，但它仍然存在于现代编程语言中。即使Scheme中先进的连续控制结构也可以被描述为复杂的后向。
在什么情况下需要使用goto?什么时候最好避免?
作为一个后续问题:C提供了一对函数setjmp()和longjmp()，它们不仅提供了在当前堆栈帧内进行跳转的能力，还提供了在任何调用帧内进行跳转的能力。这些应该被认为和goto一样危险吗?更危险?
Dijkstra自己也对这个头衔感到后悔，因为这不是他的责任。在EWD1308的结尾(也在这里。pdf)，他写道:
Finally a short story for the record.
In 1968, the Communications of the ACM
published a text of mine under the
title "The goto statement considered
harmful", which in later years would
be most frequently referenced,
regrettably, however, often by authors
who had seen no more of it than its
title, which became a cornerstone of
my fame by becoming a template: we
would see all sorts of articles under
the title "X considered harmful" for
almost any X, including one titled
"Dijkstra considered harmful". But
what had happened? I had submitted a
paper under the title "A case against
the goto statement", which, in order
to speed up its publication, the
editor had changed into a "letter to
the Editor", and in the process he had
given it a new title of his own
invention! The editor was Niklaus
Wirth.
Donald E. Knuth写了一篇关于这个主题的经典论文，它与Dijkstra的论文相匹配，那就是结构化编程与语句。阅读既有助于重建上下文，也有助于对主题的非教条性理解。在本文中，Dijkstra对这个案例的观点被报道，并且更加强烈:
Donald E. Knuth:我相信通过呈现这样一个
事实上，我并不是不同意
Dijkstra的观点，因为
他最近写道:
“请不要落入。
相信我是可怕的
教条的关于[去]的教条的
声明)。我觉得很不舒服
感觉别人在做
宗教出来了，好像
编程的概念问题
只用一个小技巧就能解决，用什么
一种简单的编码纪律!”
今天，很难看出GOTO语句有什么大不了的，因为“结构化编程”的人赢得了这场辩论，今天的语言有足够的控制流结构来避免GOTO。
计算现代C程序中goto的数量。现在添加break、continue和return语句的数量。此外，加上你使用if、else、while、switch或case的次数。这是1968年Dijkstra写这封信时，如果你用FORTRAN或BASIC语言编写程序，你的程序会有多少个goto。
当时的编程语言缺乏控制流程。例如，在最初的达特茅斯BASIC中:
IF statements had no ELSE. If you wanted one, you had to write:
100 IF NOT condition THEN GOTO 200
...stuff to do if condition is true...
190 GOTO 300
200 REM else
...stuff to do if condition is false...
300 REM end if
Even if your IF statement didn't need an ELSE, it was still limited to a single line, which usually consisted of a GOTO.
There was no DO...LOOP statement. For non-FOR loops, you had to end the loop with an explicit GOTO or IF...GOTO back to the beginning.
There was no SELECT CASE. You had to use ON...GOTO.
因此，您的程序中最终出现了许多goto。并且您不能依赖于goto限制在单个子例程中(因为GOSUB…RETURN是一个非常弱的子例程概念)，所以这些goto可以去任何地方。显然，这使得控制流难以遵循。
这就是反goto运动的由来。
我们已经讨论过这个问题了，我坚持我的观点。
此外，我受够了人们将高级语言结构描述为“伪装的goto”，因为他们显然根本没有抓住重点。例如:
即使Scheme中先进的连续控制结构也可以被描述为复杂的后向。
那完全是胡说八道。每个控制结构都可以在goto方面实现，但这个观察完全是微不足道和无用的。Goto被认为是有害的，因为它的积极影响，而是因为它的消极后果，这些已经被结构化编程消除了。
Similarly, saying “GOTO is a tool, and as all tools, it can be used and abused” is completely off the mark. No modern construction worker would use a rock and claim it “is a tool.” Rocks have been replaced by hammers. goto has been replaced by control structures. If the construction worker were stranded in the wild without a hammer, of course he would use a rock instead. If a programmer has to use an inferior programming language that doesn't have feature X, well, of course she may have to use goto instead. But if she uses it anywhere else instead of the appropriate language feature she clearly hasn't understood the language properly and uses it wrongly. It's really as simple as that.
在一个完美的世界里，我们永远不需要GOTO。然而，我们生活在一个不完美的世界。我们并没有包含我们所能想到的所有控制结构的编译器。有时我觉得使用GOTO比拼凑一个并不存在的控制结构更好。
最常见的(并不是说它很常见)是循环半结构。你总是执行第一部分，也许你执行剩下的部分，然后返回，再执行第一部分。当然，你可以在while循环中使用布尔标记来实现它，但我不喜欢这个答案，因为在我看来它不太清楚。当你看到这样的东西:
loop:
GetSomeData;
if GotData then
Begin
ProcessTheData;
StoreTheResult;
Goto Loop;
End;
对我来说，这比
Repeat
GetSomeData;
Flag := GotData;
if Flag then
Begin
ProcessTheData;
StoreTheResult;
End;
Until Not Flag;
有些时候
Function GotTheData;
Begin
GetSomeData;
Result := GotData;
End;
While GotTheData do
Begin
ProcessTheData;
StoreTheResult;
End;
不是一个可行的答案，我坚信代码应该是清晰的。如果我必须做一个注释来解释代码在做什么，我会考虑是否可以让代码更清晰，并去掉注释。
