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Synopsis:
    #include <stdarg.h>
    type va_arg( va_list param, type );

Description:
     va_arg is a macro that can be used to obtain the next argument in a
    list of variable arguments.  It must be used with the associated macros
    va_start and  va_end.  A sequence such as


         void example( char *dst, ... )
         {
             va_list curr_arg;
             int next_arg;

             va_start( curr_arg, dst );
             next_arg = va_arg( curr_arg, int );
             .
             .
             .

    causes next_arg to be assigned the value of the next variable argument.
    The argument type (which is  int in the example) is the type of the
    argument originally passed to the function.

    The macro  va_start must be executed first in order to properly
    initialize the variable curr_arg and the macro  va_end should be
    executed after all arguments have been obtained.

    The data item curr_arg is of type  va_list which contains the
    information to permit successive acquisitions of the arguments.

Returns:
    The macro returns the value of the next variable argument, according to
    type passed as the second parameter.

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

    void test_fn( const char *msg,
                  const char *types,
                  ... );

    void main()
      {
        printf( "VA...TEST\n" );
        test_fn( "PARAMETERS: 1, \"abc\", 546",
                 "isi", 1, "abc", 546 );
        test_fn( "PARAMETERS: \"def\", 789",
                 "si", "def", 789 );
      }

    static void test_fn(
      const char *msg,   /* message to be printed    */
      const char *types, /* parameter types (i,s)    */
      ... )              /* variable arguments       */
      {
        va_list argument;
        int   arg_int;
        char *arg_string;
        const char *types_ptr;

        types_ptr = types;
        printf( "\n%s -- %s\n", msg, types );
        va_start( argument, types );
        while( *types_ptr != '\0' ) {
          if (*types_ptr == 'i') {
            arg_int = va_arg( argument, int );
            printf( "integer: %d\n", arg_int );
          } else if (*types_ptr == 's') {
            arg_string = va_arg( argument, char * );
            printf( "string:  %s\n", arg_string );
          }
          ++types_ptr;
        }
        va_end( argument );
      }

    produces the following:

    VA...TEST

    PARAMETERS: 1, "abc", 546 -- isi
    integer: 1
    string:  abc
    integer: 546

    PARAMETERS: "def", 789 -- si
    string:  def
    integer: 789

Classification:
    ANSI

Systems:
    MACRO
See Also:
    va_end, va_start, vfprintf, vprintf, vsprintf