“错误:参数太少，无法运行”

I have a C program called opencv2.0 function :

我有一个C程序，叫做opencv2.0功能:

cvSaveImage( out_img_name, img);

Compiler gcc reports that

编译器gcc报道,

too few arguments to function cvSaveImage

函数cvSaveImage的参数太少

The prototype of cvSaveImage in highgui.h is

在highgui中cvSaveImage的原型。h是

CVAPI(int) cvSaveImage( const char* filename, const CvArr* image, const int* params CV_DEFAULT(0) )

CVAPI(int) cvSaveImage(const char* filename, const CvArr* image, const int* params CV_DEFAULT(0))

After I change my call to be

在我把我的电话改为

cvSaveImage( out_img_name, img, 0);

The compilation is finally successful. Does it mean default values of arguments for function are only supported in C++ but not C?

编译终于成功了。它是否意味着函数参数的默认值仅在c++中支持，而在C中不支持?

Thanks and regards!

感谢和问候!

2 个解决方案

#1

Correct - Standard C does not support default arguments, neither in the C89 standard nor in the C99 standard (nor in the C2011 standard). There may be compiler-specific extensions to support it in some compilers, but it is not standard.

正确-标准C不支持默认参数，无论是C89标准还是C99标准(也不是C2011标准)。在某些编译器中可能有特定于编译器的扩展来支持它，但它不是标准的。

#2

C requires a special notation if you want to use a variable number of arguments.

如果要使用可变数量的参数，C需要一个特殊的符号。

http://www.swig.org/Doc1.3/Varargs.html

You can't define a default variable to be passed in to a plain function. You could set-up a macro that auto-magically passes in a default value and use that as your function entry if you want to.

不能定义要传递给普通函数的默认变量。您可以设置一个宏，该宏自动地传入一个默认值，如果您愿意，可以将其用作函数条目。

#1