VARARGS(5)                                                          VARARGS(5)



NAME
     varargs - variable argument list

SYNOPSIS
     #include <varargs.h>

     function(vaalist)
     vadcl
     valist pvar;
     vastart(pvar);
     f = vaarg(pvar, type);
     vaend(pvar);

DESCRIPTION
     This set of macros provides a means of writing portable procedures that
     accept variable argument lists.  Routines having variable argument lists
     (such as printf(3)) that do not use varargs are inherently nonportable,
     since different machines use different argument passing conventions.

     PLEASE NOTE: varargs is being supplanted by stdarg(5). Users should
     reference that man page for the recommended method of passing variable
     argument lists.

     vaalist is used in a function header to declare a variable argument
     list.

     vadcl is a declaration for vaalist.  Note that there is no semicolon
     after vadcl.

     valist is a type which can be used for the variable pvar, which is used
     to traverse the list.  One such variable must always be declared.

     vastart(pvar) is called to initialize pvar to the beginning of the list.

     vaarg(pvar, type) will return the next argument in the list pointed to
     by pvar.  Type is the type to which the expected argument will be
     converted when passed as an argument.  In standard C, arguments that are
     char or short should be accessed as int, unsigned char or unsigned short
     are converted to unsigned int, and float arguments are converted to
     double.  Different types can be mixed, but it is up to the routine to
     know what type of argument is expected, since it cannot be determined at
     runtime.

     vaend(pvar) is used to finish up.

     Multiple traversals, each bracketed by vastart ...  vaend, are
     possible.

EXAMPLE
          #include <varargs.h>
          execl(vaalist)
          vadcl



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VARARGS(5)                                                          VARARGS(5)



         {
               valist ap;
               char *file;
               char *args[100];
               int argno = 0;

               vastart(ap);
               file = vaarg(ap, char *);
               while (args[argno++] = vaarg(ap, char *))
                    ;
               vaend(ap);
               return execv(file, args);
          }

SEE ALSO
     stdarg(5)

BUGS
     It is up to the calling routine to determine how many arguments there
     are, since it is not possible to determine this from the stack frame.
     For example, execl passes a 0 to signal the end of the list.  Printf can
     tell how many arguments are supposed to be there by the format.

     The macros va_start and va_end may be arbitrarily complex; for example,
     va_start might contain an opening brace, which is closed by a matching
     brace in va_end.  Thus, they should only be used where they could be
     placed within a single complex statement.




























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