C Library -

The stdarg.h header defines a variable type va_list and three macros which can be used to get the arguments in a function when the number of arguments are not known i.e. variable number of arguments.
A function of variable arguments is defined with the ellipsis (,...) at the end of the parameter list.

Library Variables

Following is the variable type defined in the header stdarg.h −

S.N.	Variable & Description
1	va_list This is a type suitable for holding information needed by the three macros va_start(), va_arg() and va_end().

Library Macros

Following are the macros defined in the header stdarg.h −

S.N.	Macro & Description
1	void va_start(va_list ap, last_arg) This macro initializes ap variable to be used with the va_arg and va_end macros. The last_arg is the last known fixed argument being passed to the function i.e. the argument before the ellipsis.
2	type va_arg(va_list ap, type) This macro retrieves the next argument in the parameter list of the function with type type.
3	void va_end(va_list ap) This macro allows a function with variable arguments which used the va_start macro to return. If va_end is not called before returning from the function, the result is undefined.