问题描述
GCC选项应该设置为尽可能严格GCC? (并且我的意思是尽可能严格)我在C89中编写代码,并希望我的代码符合ANSI / ISO标准。我推荐使用:
-Wall -Wextra -std = c89 -pedantic -Wmissing-prototypes -Wstrict-prototypes \
-Wold-style-definition
您应该使用 -O
以及 -g
,因为一些警告仅在使用优化器时可用(实际上,我通常使用 -O3
来发现问题)。您可能更喜欢 -std = gnu89
,因为这会禁用库中较少的扩展名。 OTOH,如果你编码严格的ANSI C89,也许你希望他们禁用。 -ansi
选项相当于 -std = c89
,但不像显式或灵活。
缺少的原型会警告您在使用的函数(或定义的外部函数)时没有范围原型。严格的原型意味着你不能在函数声明或定义(或函数指针)中使用'空括号';你需要(void)
或正确的参数列表。旧样式定义点K& R样式函数定义,如:
int old_style(a,b)int a;双b; {...}
如果幸运的话,您不必担心这一点。我在工作中并不那么幸运,而且我也不能使用严格的原型,对我的懊恼来说,因为周围有太多松散的函数指针,所以我不能使用严格的原型。
另见:
What GCC options should be set to have GCC as strict as possible? (and I do mean as strict as possible) I'm writing in C89 and want my code to be ANSI/ISO compliant.
I'd recommend using:
-Wall -Wextra -std=c89 -pedantic -Wmissing-prototypes -Wstrict-prototypes \
-Wold-style-definition
You should compile with -O
as well as -g
as some warnings are only available when the optimizer is used (actually, I usually use -O3
for spotting the problems). You might prefer -std=gnu89
as that disables fewer extensions in the libraries. OTOH, if you're coding to strict ANSI C89, maybe you want them disabled. The -ansi
option is equivalent to -std=c89
but not quite as explicit or flexible.
The missing prototypes warns you about functions which are used (or external functions defined) without a prototype in scope. The strict prototypes means you can't use 'empty parentheses' for function declarations or definitions (or function pointers); you either need (void)
or the correct argument list. The old style definition spots K&R style function definitions, such as:
int old_style(a, b) int a; double b; { ... }
If you're lucky, you won't need to worry about that. I'm not so lucky at work, and I can't use strict prototypes, much to my chagrin, because there are too many sloppy function pointers around.
See also: What is the best command-line tool to clean up code
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