Command-line argument parsing
Different command-line argument parsing methods are used by different programming languages to parse command-line arguments.
Programming languages
C
C uses argv to process command-line arguments.[1][2]
An example of C argument parsing would be: <syntaxhighlight lang="c">
- include <stdio.h>
int main (int argc, char *argv[]) {
int count;
for (count = 0; count < argc; count++)
puts (argv[count]);
} </syntaxhighlight> C also has functions called getopt and getopt_long.
C#
An example of C# argument parsing would be: <syntaxhighlight lang="csharp"> class Program {
static void Main(string[] args)
{
foreach (var arg in args)
Console.WriteLine(arg);
}
} </syntaxhighlight>
Java
An example of Java argument parsing would be: <syntaxhighlight lang="java"> public class Echo {
public static void main (String[] args) {
for (String s: args) {
System.out.println(s);
}
}
} </syntaxhighlight>
Kotlin
Here are some possible ways to print arguments in Kotlin:[3]
<syntaxhighlight lang="kotlin"> fun main(args: Array<String>) = println(args.joinToString()) </syntaxhighlight>
<syntaxhighlight lang="kotlin"> fun main(args: Array<String>) = println(args.contentToString()) </syntaxhighlight>
<syntaxhighlight lang="kotlin"> fun main(args: Array<String>) {
for (arg in args)
println(arg)
} </syntaxhighlight>
Perl
Perl uses @ARGV.
<syntaxhighlight lang="perl"> foreach $arg (@ARGV)GT {
print $arg;
} </syntaxhighlight>FT or <syntaxhighlight lang="perl"> foreach $argnum (0 .. $#ARGV)ST {
print $ARGV[$argnum];
} </syntaxhighlight>
AWK
AWK uses ARGV also.
<syntaxhighlight lang="awk"> BEGIN {
for ( i = 0; i < ARGC; i++ )
{
print ARGV[i]
}
} </syntaxhighlight>
PHP
PHP uses argc as a count of arguments and argv as an array containing the values of the arguments.[4][5] To create an array from command-line arguments in the -foo:bar format, the following might be used:
<syntaxhighlight lang="php"> $args = parseArgs($argv); echo getArg($args, "foo");
function parseArgs(array $args) {
foreach ($args as $arg) {
$tmp = explode(":", $arg, 2);
if ($arg[0] === "-") {
$args[substr($tmp[0], 1)] = $tmp[1];
}
}
return $args;
}
function getArg(array $args, string $arg) {
if (isset($args[$arg])) {
return $args[$arg];
}
return false;
} </syntaxhighlight>
PHP can also use getopt().[6]
Python
Python uses sys.argv, e.g.:
<syntaxhighlight lang="python">
import sys
for arg in sys.argv:
print arg
</syntaxhighlight>
Python also has a module called argparse in the standard library for parsing command-line arguments.[7]
Racket
Racket uses a current-command-line-arguments parameter, and provides a racket/cmdline[8] library for parsing these arguments. Example:
<syntaxhighlight lang="racket">
- 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 <char> for the eyes" (eyes char)])
(printf "~a~a~a\n"
(eyes)
(if (nose?) "-" "")
(if (smile?) ")" "("))
</syntaxhighlight>
The library parses long and short flags, handles arguments, allows combining short flags, and handles -h and --help automatically:
<syntaxhighlight lang="console">
$ racket /tmp/c -nfe 8
8-(
</syntaxhighlight>
Rexx
Rexx uses arg, e.g.:
<syntaxhighlight lang="rexx">
do i=1 to words(arg(1))
say word(arg(1), i)
end
</syntaxhighlight>
Rust
The args are in env::args().[9]
<syntaxhighlight lang="rust">
use std::env;
fn main() {
let args: Vec<String> = env::args().collect();
let query = &args[1]; let file_path = &args[2];
println!("Searching for {}", query);
println!("In file {}", file_path);
} </syntaxhighlight>
JavaScript
Node.js
JavaScript programs written for Node.js use the process.argv global variable.[10]
<syntaxhighlight lang="javascript"> // argv.js console.log(process.argv); </syntaxhighlight>
<syntaxhighlight lang="bash"> $ node argv.js one two three four five [ 'node',
'/home/avian/argvdemo/argv.js', 'one', 'two', 'three', 'four', 'five' ]
</syntaxhighlight>
Node.js programs are invoked by running the interpreter node interpreter with a given file, so the first two arguments will be node and the name of the JavaScript source file. It is often useful to extract the rest of the arguments by slicing a sub-array from process.argv.[11]
<syntaxhighlight lang="javascript"> // process-args.js console.log(process.argv.slice(2)); </syntaxhighlight>
<syntaxhighlight lang="bash"> $ node process-args.js one two=three four [
'one', 'two=three', 'four' ]
</syntaxhighlight>
Bun
JavaScript written for Bun use Bun.argv and the util.parseArgs function.[12]
<syntaxhighlight lang="javascript"> console.log(Bun.argv); </syntaxhighlight>
Deno
JavaScript written for [[Deno (software)|Deno] use Deno.args[13] and the parseArgs function.[14]
<syntaxhighlight lang="javascript"> console.log(Deno.args); </syntaxhighlight>
References
- ^ "The C Book — Arguments to main". Publications.gbdirect.co.uk. Retrieved 2010-05-31.
- ^ An example of parsing C arguments and options
- ^ "Kotlin: Basic syntax". Retrieved 2022-05-13.
- ^ "PHP Manual". PHP. Retrieved 2010-05-31.
- ^ wikibooks:PHP Programming/CLI
- ^ "PHP: Getopt - Manual".
- ^ "argparse — Parser for command-line options, arguments and sub-commands". Python v3.10.0 documentation. Archived from the original on 2012-11-01. Retrieved 15 October 2021.
- ^ The Racket reference manual, Command-Line Parsing
- ^ "Accepting Command Line Arguments - The Rust Programming Language". doc.rust-lang.org. Retrieved 22 December 2022.
- ^ "process.argv". Node.js v10.16.3 Documentation. Retrieved 3 October 2019.
- ^ "How to parse command line arguments". Node.js Foundation Documentation. Retrieved 3 October 2019.
- ^ "Parse command-line arguments | Bun Examples". Bun.
- ^ "Deno.args". docs.deno.com.
- ^ "parseArgs from parse-args - @std/cli - JSR". jsr.io.