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NAME
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ARGBEGIN, ARGEND, ARGC, ARGF, EARGF, arginit, argopt – process
option letters from argv
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SYNOPSIS
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#include <u.h>
#include <libc.h>
ARGBEGIN {
char *ARGF();
char *EARGF(code);
Rune ARGC();
} ARGEND
extern char *argv0;
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DESCRIPTION
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These macros assume the names argc and argv are in scope; see
exec(3). ARGBEGIN and ARGEND surround code for processing 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 character,
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.
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EXAMPLE
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This C program can take option b and option f, which requires
an argument.
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#include <u.h>
#include <libc.h>
void
main(int argc, char *argv[])
{
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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);
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}
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Here is the output from running the command prog −bffile1 −r −f
file2 arg1 arg2
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prog −b −f(file1) badflag('r') −f(file2) 2 args: 'arg1' 'arg2'
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SOURCE
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