“Command-line argument parsing”的意思、由来-开放百科全书

Programming languages

C uses argv to process command-line arguments.^[1]^[2]

An example of C argument parsing would be:

include

int main (int argc, char *argv[])

int count; for (count=0; count

}

Java

An example of Java argument parsing would be:

public class Echo {

    public static void main (String[] args) {        for (String s: args) {            System.out.println(s);        }    }

}

Perl

Perl uses $ARGV.

foreach $arg (@ARGV)

{

}

foreach $argnum (0 .. $#ARGV)

{

}

AWK

AWK uses ARGV also.

BEGIN {

   for ( i = 0; i < ARGC; i++ )   {       print ARGV[i]   }

}

PHP

PHP uses argc as a count of arguments and argv as an array containing the values of the arguments.^[3]^[4] To create an array from command-line arguments in the -foo:bar format, the following might be used:

$args = parseArgs($argv);

echo getArg($args, 'foo');

function parseArgs($args) {

    foreach($args as $arg) {        $tmp = explode(':', $arg, 2);        if ($arg[0] === '-') {            $args[substr($tmp[0], 1)] = $tmp[1];        }    }    return $args;

}

function getArg($args, $arg) {

    if (isset($args[$arg])) {        return $args[$arg];    }    return false;

}

PHP can also use getopt().^[5]

Python

Python uses sys.argv, e.g.:

import sys

for arg in sys.argv:

Python also has a module called argparse in the standard library for parsing command-line arguments.^[6]

Racket

Racket uses a current-command-line-arguments parameter, and provides a racket/cmdline^[7] library for parsing these arguments. Example:

lang racket

(require racket/cmdline)

(define smile? (make-parameter #t))

(define nose? (make-parameter #false))

(define eyes (make-parameter ":"))

(command-line #:program "emoticon"

              #:once-any ; the following two are mutually exclusive              [("-s" "--smile") "smile mode" (smile? #true)]              [("-f" "--frown") "frown mode" (smile? #false)]

              #:once-each              [("-n" "--nose") "add a nose"  (nose? #true)]              [("-e" "--eyes") char "use  for the eyes" (eyes char)])

(printf "~a~a~a\"

        (eyes)        (if (nose?) "-" "")        (if (smile?) ")" "("))

The library parses long and short flags, handles arguments, allows combining short flags, and handles -h and --help automatically:

$ racket /tmp/c -nfe 8

8-(

References

1. ^{{cite web|url=http://publications.gbdirect.co.uk/c_book/chapter10/arguments_to_main.html |title=The C Book — Arguments to main |publisher=Publications.gbdirect.co.uk |date= |accessdate=2010-05-31}}
2. ^An example of parsing C arguments and options
3. ^{{cite web|url=http://php.net/manual/en/reserved.variables.argv.php |title=PHP Manual |publisher=PHP |date= |accessdate=2010-05-31}}
4. ^PHP Programming/CLI
5. ^https://php.net/getopt
6. ^{{cite web|title=argparse — Parser for command-line options, arguments and sub-commands|url=https://docs.python.org/library/argparse.html|work=Python v2.7.2 documentation|accessdate=7 March 2012}}
7. ^The Racket reference manual, Command-Line Parsing

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