visual-studio 如何处理 Visual Studio 2008 中的警告 C4100
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How to deal with Warning C4100 in Visual Studio 2008
提问by Jimmie
For some reason my Visual Studio 2008 began to show warnings for code like: "int main( int argc, char **argv)", which is really annoying.
出于某种原因，我的 Visual Studio 2008 开始显示代码警告，例如：“int main(int argc, char **argv)”，这真的很烦人。
The detailed warning ouputs are (you can ignore the line numbers):
1>.\main.cpp(86) : warning C4100: 'argv' : unreferenced formal parameter
1>.\main.cpp(86) : warning C4100: 'argc' : unreferenced formal parameter
详细的警告输出是（您可以忽略行号）：
1>.\main.cpp(86) : warning C4100: 'argv' : unreferencedformal parameter
1>.\main.cpp(86) : warning C4100: ' argc' : 未引用的形式参数
I wonder if there are settings in Visual Studio 2008 that have been accidentally changed. Or how should I deal with this warning?
我想知道Visual Studio 2008 中是否有不小心更改的设置。或者我应该如何处理这个警告？
回答by James McNellis
If the parameters are unreferenced, you can leave them unnamed:
如果参数未引用，您可以不命名它们：
int main(int, char**)
{
}
instead of
代替
int main(int argc, char** argv)
{
}
If you really want just to suppress the warning, you can do so using the /wd4100command line option to the compiler or using #pragma warning(disable: 4100)in your code.
如果您真的只想取消警告，您可以使用/wd4100编译器的命令行选项或#pragma warning(disable: 4100)在您的代码中使用。
This is a level 4 warning; if you compile at a lower warning level, you won't get this warning. The warning level is set in the project properties (right-click project, select Properties; on the Configuration Properties -> C++ -> General, set "Warning Level").
这是 4 级警告；如果您在较低的警告级别进行编译，您将不会收到此警告。警告级别在项目属性中设置（右键项目，选择属性；在Configuration Properties -> C++ -> General，设置“Warning Level”）。
回答by CB Bailey
If you're not using the command line parameters then the other standard signature for main is:
如果您不使用命令行参数，那么 main 的另一个标准签名是：
int main();
回答by Michael Burr
Warning C4100 is issued at warning level 4 which is not default, so at some point someone probably changed it for your project.
警告 C4100 在警告级别 4 发出，这不是默认值，因此在某些时候有人可能为您的项目更改了它。
You could change the warning level back, or address the warning more directly.
您可以更改警告级别，或者更直接地解决警告。
As James McNellis said, you can silence the warning in C++ by removing the parameter name from the parameter list. However, if the code will be compiled as C code you'll get an error in that case.
正如James McNellis 所说，您可以通过从参数列表中删除参数名称来消除 C++ 中的警告。但是，如果代码将被编译为 C 代码，在这种情况下您将收到错误消息。
The Windows headers define the macro UNREFERENCED_PARAMETER()to help deal with this warning. You could use
Windows 标头定义了UNREFERENCED_PARAMETER()帮助处理此警告的宏。你可以用
UNREFERENCED_PARAMETER( argc);
UNREFERENCED_PARAMETER( argv);
to silence the warning. If you don't want to include windows headers, the macro simply expands to a use of the parameter name in a do nothing expression:
使警告静音。如果您不想包含 Windows 标题，则宏只是扩展为在无操作表达式中使用参数名称：
#define UNREFERENCED_PARAMETER(P) \
/*lint -save -e527 -e530 */ \
{ \
(P) = (P); \
} \
/*lint -restore */
