额外的逗号 [英] extra comma
问题描述
大家好，
为什么C语言在初始化列表中允许额外的逗号
ex： - int days [] = {
31,28.31,30,31,30，
31,31,30,31,30,31，
}
i听说它是为了自动代码生成的目的
还有除此之外的其他目的，如果是这样的原因...... ????
Hi all,
why does C language permits an extra comma in initializer list
ex:- int days[] = {
31,28.31,30,31,30,
31,31,30,31,30,31,
}
i have heard it is for the purpose of automatic code generation
is there any other purpose than this, if so why ...????
推荐答案
aa*****@gmail.com 说：
大家好，
为什么C语言在初始化列表中允许额外的逗号
ex： - int days [] = {
31,28.31,30,31,30，
Hi all,
why does C language permits an extra comma in initializer list
ex:- int days[] = {
31,28.31,30,31,30,
31到28之间你意思是，不是..
Between 31 and 28 you meant ,, not ..
31,31,30,31,30,31，
}
i听说它是为了自动代码生成的目的
31,31,30,31,30,31,
}
i have heard it is for the purpose of automatic code generation
那应该是这种跛脚背后的原因，是的。但
观察：
i = 0;
printf（"％d"，day [i]）;
while（i ++< 12）
{
printf（"，％d％s"，day [i]，（i％6） ）== 5？" \ n"：""）;
}
所以，正如你所看到的，它不是''实际上很难生成代码
没有尾随逗号。
That''s supposed to be the reasoning behind such lamenesses, yes. But
observe:
i = 0;
printf(" %d", day[i]);
while(i++ < 12)
{
printf(", %d%s", day[i], (i % 6) == 5 ? "\n" : "");
}
So, as you can see, it isn''t actually difficult to generate the code
without the trailing comma.
还有其他目的，如果是这样，为什么...... ????
is there any other purpose than this, if so why ...????
不，它只是为懒人提供服务。
-
Richard Heathfield< http://www.cpax.org.uk>
电子邮件：-http：// www。 + rjh @
谷歌用户：< http://www.cpax.org.uk/prg/writings/googly.php>
Usenet是一个奇怪的放置" - dmr 1999年7月29日
No, it''s just catering for the lazy.
--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999
2月16日晚上7点14分，Richard Heathfield< r ... @ see.sig.invalidwrote：
On Feb 16, 7:14 pm, Richard Heathfield <r...@see.sig.invalidwrote:
aark ... @ gmail.com说：
aark...@gmail.com said:
大家好，
Hi all,
为什么C语言在初始化列表中允许额外的逗号
why does C language permits an extra comma in initializer list
ex： - int days [] = {
31,28.31,30,31,30，
ex:- int days[] = {
31,28.31,30,31,30,
在31到28之间你的意思是，不是..
Between 31 and 28 you meant ,, not ..
你怎么知道的？ 28.31是在整数
上下文中初始化的有效值。
How do you know? 28.31 is a valid value for initializing in integer
context.
>
>
31,31,30,31,30,31，
}
i听说是为了自动代码生成的目的
31,31,30,31,30,31,
}
i have heard it is for the purpose of automatic code generation
这应该是这种跛脚背后的原因，是的。但
观察：
i = 0;
printf（"％d"，day [i]）;
while（i ++< 12）
{
printf（"，％d％s"，day [i]，（i％6） ）== 5？" \ n"：""）;
}
所以，正如你所看到的，在没有尾随逗号的情况下生成代码
实际上并不困难。
That''s supposed to be the reasoning behind such lamenesses, yes. But
observe:
i = 0;
printf(" %d", day[i]);
while(i++ < 12)
{
printf(", %d%s", day[i], (i % 6) == 5 ? "\n" : "");
}
So, as you can see, it isn''t actually difficult to generate the code
without the trailing comma.
模数甚至条件检查在某些地方可能很贵我想b $ b猜测。
注意它是'不仅允许在初始化列表中使用但在任何地方
使用{elements}。 （我不知道它的正确用语）
例如，printf（"％zu \ n"，sizeof（char []）{1,2,3，}） ;
Modulus or even the conditional check could be expensive somewhere I
guess.
Notice it''s not only allowed in an "initializer list" but anywhere
where {elements} is used. (I don''t know the proper term for it)
For example, printf("%zu\n", sizeof (char[]){1,2,3,});
2月16日，4：55 * pm，aark ... @ gmail.com写道：
On Feb 16, 4:55*pm, aark...@gmail.com wrote:
为什么C语言在初始化列表中允许额外的逗号
...
*我听说它是为了自动代码生成的目的
还有除此之外的任何其他目的，如果是这样，为什么...... ????
why does C language permits an extra comma in initializer list
...
*i have heard it is for the purpose of automatic code generation
is there any other purpose than this, if so why ...????
根据K& R2（第196页），这是整洁格式的精确。
-
马丁
According to K&R2 (p196) it is "a nicety for neat formatting."
--
Martin
这篇关于额外的逗号的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
