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