不定参数宏的__VA_ARGS__遍历和参数个数计算_宏函数参数遍历-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_39570293/article/details/91959038

本文介绍了如何在C语言中使用不定参数宏的__VA_ARGS__进行遍历处理，并探讨了如何计算宏参数的个数，参考了多个技术资源。

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//遍历不定参数，不定参数展开 <=9个 
//vs中这种方式定义宏过度也不能用
#define  EXTAND_ARGS(args) args //__VA_ARGS__在vs中会被认为是一个实参，所以需要定义该宏过度

#define FOR_EACH_1(what,ParamType, ...) what(ParamType,1)
#define FOR_EACH_2(what,ParamType, ...) what(ParamType,2), EXTAND_ARGS(FOR_EACH_1(what, __VA_ARGS__))
#define FOR_EACH_3(what,ParamType, ...) what(ParamType,3), EXTAND_ARGS(FOR_EACH_2(what, __VA_ARGS__))
#define FOR_EACH_4(what,ParamType, ...) what(ParamType,4), EXTAND_ARGS(FOR_EACH_3(what, __VA_ARGS__))
#define FOR_EACH_5(what,ParamType, ...) what(ParamType,5), EXTAND_ARGS(FOR_EACH_4(what, __VA_ARGS__))
#define FOR_EACH_6(what,ParamType, ...) what(ParamType,6), EXTAND_ARGS(FOR_EACH_5(what, __VA_ARGS__))
#define FOR_EACH_7(what,ParamType, ...) what(ParamType,7), EXTAND_ARGS(FOR_EACH_6(what, __VA_ARGS__))
#define FOR_EACH_8(what,ParamType, ...) what(ParamType,8), EXTAND_ARGS(FOR_EACH_7(what, __VA_ARGS__))
#define FOR_EACH_9(what,ParamType, ...) what(ParamType,9), EXTAND_ARGS(FOR_EACH_8(what, __VA_ARGS__))


#define CONCATENATE(arg1, arg2)  arg1##arg2

//Parameters Table
#define PARAM_TABLE(ParamType,N) ParamType param##N
#define PARAM_TABLE_FOR_EACH_(N,...) EXTAND_ARGS(CONCATENATE(FOR_EACH_, N)(PARAM_TABLE,__VA_ARGS__))

// Parameters Name
#define PARAM_NAME(ParamType,N) param##N
#define PARAM_NAME_FOR_EACH_(N,...) EXTAND_ARGS(CONCATENATE(FOR_EACH_, N)(PARAM_NAME,__VA_ARGS__))


// 计算 __VA_ARGS__ 参数个数,最大支持64个参数 //vs中无参数时会返回1
#define FL_ARG_COUNT(...) EXTAND_ARGS(FL_INTERNAL_ARG_COUNT_PRIVATE(0, __VA_ARGS__,\
	64, 63, 62, 61, 60, \
	59, 58, 57, 56, 55, 54, 53, 52, 51, 50, \
	49, 48, 47, 46, 45, 44, 43, 42, 41, 40, \
	39, 38, 37, 36, 35, 34, 33, 32, 31, 30, \
	29, 28, 27, 26, 25, 24, 23, 22, 21, 20, \
	19, 18, 17, 16, 15, 14, 13, 12, 11, 10, \
	9,  8,  7,  6,  5,  4,  3,  2,  1,  0))
#define FL_INTERNAL_ARG_COUNT_PRIVATE(\
	_0,  _1,  _2,  _3,  _4,  _5,  _6,  _7,  _8,  _9, \
	_10, _11, _12, _13, _14, _15, _16, _17, _18, _19, \
	_20, _21, _22, _23, _24, _25, _26, _27, _28, _29, \
	_30, _31, _32, _33, _34, _35, _36, _37, _38, _39, \
	_40, _41, _42, _43, _44, _45, _46, _47, _48, _49, \
	_50, _51, _52, _53, _54, _55, _56, _57, _58, _59, \
	_60, _61, _62, _63, _64, N, ...) N


#define  DeclarationAndDifinitionInterface(funcName,...) \
	virtual NPSDKError funcName(PARAM_TABLE_FOR_EACH_(EXTAND_ARGS(FL_ARG_COUNT(__VA_ARGS__)),__VA_ARGS__))      \
	{                                                  \
		if (pImpl != NULL)                             \
		{                                              \
			return pImpl->funcName(PARAM_NAME_FOR_EACH_(EXTAND_ARGS(FL_ARG_COUNT(__VA_ARGS__)),__VA_ARGS__));    \
		}                                              \
		return NPSDK_ERR_NOT_SUPPORT;                  \
	}