有没有什么方法可以在 gcc 中启用 for(int i=0; ... 而不必打开 c99 模式
我有一个非常大的程序，它用 gcc 编译而没有警告。
如果我在命令行上打开 c99 模式 --std=c99 ，它会给出大量警告和错误。
但我喜欢用 for(int i=0; i<20; i++){ code }
代替 {int i; for (i=0; i<20; i++){ code }}
有没有办法告诉 gcc 允许这个并且只允许这个？
或者，有什么方法可以在我正在处理的特定功能中启用 c99 模式吗？像这样的东西
#pragma c99 on
for(int i=0; i<99; i++)
{
code
}
#pragma c99 off
I've got a very big program which compiles with gcc without warnings.
If I turn on c99 mode --std=c99 on the command line, it gives a huge number of warnings and errors.
But I love the idiom for(int i=0; i<20; i++){ code }
in place of {int i; for (i=0; i<20; i++){ code }}
Is there any way to tell gcc to allow this and only this?
Alternatively, is there any way to enable c99 mode in the particular functions I'm working on? Something like
#pragma c99 on
for(int i=0; i<99; i++)
{
code
}
#pragma c99 off
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警告和错误很可能是因为
-std=c99请求符合标准的 C99，这意味着未定义许多污染 C99 命名空间的特定于平台的函数。相反，您应该尝试
--std=gnu99，它是相当于gnu89默认模式的 C99。It is likely that the warnings and errors are because
-std=c99requests standard-conforming C99, which means that many platform-specific functions that pollute the C99 namespace are not defined.Instead, you should try
--std=gnu99, which is the C99-equivalent to the default mode ofgnu89.或者使用-std=gnu99，您可以禁用单个警告：
阅读info gcc：
`-Wdeclaration-after-statement (C and Objective-C only)' Warn when a declaration is found after a statement in a block. This construct, known from C++, was introduced with ISO C99 and is by default allowed in GCC. It is not supported by ISO C90 and was not supported by GCC versions before GCC 3.0. *Note Mixed Declarations::.Alternatively to use -std=gnu99 you can disable individual warnings:
Read info gcc:
`-Wdeclaration-after-statement (C and Objective-C only)' Warn when a declaration is found after a statement in a block. This construct, known from C++, was introduced with ISO C99 and is by default allowed in GCC. It is not supported by ISO C90 and was not supported by GCC versions before GCC 3.0. *Note Mixed Declarations::.