ARG(3) ARG(3)
NAME
ARGBEGIN, ARGEND, ARGC, ARGF, EARGF, arginit, argopt -
process option letters from argv
SYNOPSIS
#include <u.h>
#include <libc.h>
ARGBEGIN {
char *ARGF();
char *EARGF(code);
Rune ARGC();
} ARGEND
extern char *argv0;
DESCRIPTION
These macros assume the names argc and argv are in scope;
see exec(3). ARGBEGIN and ARGEND surround code for process-
ing program options. The code should be the cases of a C
switch on option characters; it is executed once for each
option character. Options end after an argument --, before
an argument -, or before an argument that doesn't begin with
-.
The function macro ARGC returns the current option charac-
ter, as an integer.
The function macro ARGF returns the current option argument:
a pointer to the rest of the option string if not empty, or
the next argument in argv if any, or 0. ARGF must be called
just once for each option that takes an argument. The macro
EARGF is like ARGF but instead of returning zero runs code
and, if that returns, calls abort(3). A typical value for
code is usage(), as in EARGF(usage()).
After ARGBEGIN, argv0 is a copy of argv[0] (conventionally
the name of the program).
After ARGEND, argv points at a zero-terminated list of the
remaining argc arguments.
EXAMPLE
This C program can take option b and option f, which
requires an argument.
#include <u.h>
#include <libc.h>
void
main(int argc, char *argv[])
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ARG(3) ARG(3)
{
char *f;
print("%s", argv[0]);
ARGBEGIN {
case 'b':
print(" -b");
break;
case 'f':
print(" -f(%s)", (f=ARGF())? f: "no arg");
break;
default:
print(" badflag('%c')", ARGC());
} ARGEND
print(" %d args:", argc);
while(*argv)
print(" '%s'", *argv++);
print("\n");
exits(nil);
}
Here is the output from running the command prog -bffile1 -r
-f file2 arg1 arg2
prog -b -f(file1) badflag('r') -f(file2) 2 args: 'arg1'
'arg2'
SOURCE
/usr/local/plan9/include/libc.h
Page 2 Plan 9 (printed 11/18/24)