va_arg - process variable argument list

Syntax	#include <stdarg.h> Optional #include <varargs.h> (End) type va_arg(va_list ap, type);
Description	The va_arg, va_start and va_end macros allow portable procedures that accept variable argument lists, as defined in stdarg.h, to be written. They are used to process a list of arguments which may vary in number and type at each function call. va_arg returns the data type and value of the next argument in a variable argument list ap, starting with the first argument. Technically speaking, the macro expands into an expression of the data type and value of the argument. The variable argument list to which ap points must be initialized with va_start before the first call to va_arg. Each invocation of va_arg modifies ap so that the value of the next argument in turn is returned. ap is a pointer to the argument list initialized with va_start before va_arg is called for the first time. type is a type name matching the type of the current argument. Any C data type, for which a pointer to an object of the specified type is defined by simply appending an * to type, is allowed. Array and function types, for example, are invalid. If there is no next argument or if type does not match the current argument, the behavior is undefined.
Return val.	Value of the first argument when va_arg() is called for the first time after va_start. This argument comes after the last "named" argument parmN in the formal parameter list (see also va_start()). Subsequent calls return the remaining argument values in succession.
Notes	Compatibility of argument types is supported by the C runtime system to the extent that similar types are stored in the same way in the parameter list, i.e.: all unsigned types (including char) are represented as unsigned int (right-justified in a word), and all other integer types are represented as int (right-justified in a word). float is represented as double (right-justified in a doubleword). The va_end macro must be called before returning from a function whose argument list was processed with va_arg.
See also	va_start(), va_end(), stdarg.h, varargs.h.