In this post, I was write as we can get the parameters given to a function in language C, using stdarg library, that declares a type va_list and defines three macros for stepping through a list of arguments whose number and types are not known to the called function.

Below is show the declared functions in stdarg:

#include <stdarg.h>

void va_start( va_list ap, last );
type va_arg( va_list ap, type );
void va_end( va_list ap );
void va_copy( va_list dest, va_list src );

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#include <stdio.h>
#include <stdarg.h>

void read_names( char *name_main, ... )
{
        va_list args;
        va_start( args, name_main );

        char *name1 = va_arg( args, char * );
        char *name2 = va_arg( args, char * );

        fprintf( stdout, "%s => %s and %s\n", name_main, name1, name2 );
        va_end( args );
}

int
main()
{
        read_names( "Main name", "second name", "third name" );
}

As shown above, we can see that use the function va_start, which is declared in stdarg.h header. This function is responsible to get a varying number of arguments of varying types.

The var_start macro, initializes va_list for subsequent use by va_arg() and va_end(), and must be called first.