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 −
| Sr.No. | 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().
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Library Macros
Following are the macros defined in the header stdarg.h −
| Sr.No. | 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.
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| 2 | type va_arg(va_list ap, type)
This macro retrieves the next argument in the parameter list of the function with type type.
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| 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_endis not called before returning from the function, the result is undefined.
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