Extract file extension: Difference between revisions

{{draft task}}

 

 

 

 

 

=={{header|ALGOL 68}}==

{{works with|ALGOL 68G|Any - tested with release 2.8.win32}}

# defined as a dot followed by one or more letters or digits #

OP EXTENSION = ( STRING pathname )STRING:

main:

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<pre>

 

=={{header|ALGOL W}}==

% extracts a file-extension from the end of a pathname. %

% The file extension is defined as a dot followed by one or more letters %

end ; % text extension %

 

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<pre>

</pre>

 

=={{header|AWK}}==

BEGIN {

arr[++i] = "picture.jpg"

arr[++i] = "/path/to.my/file"

arr[++i] = "file.odd_one"

for (j=1; j<=i; j++) {

printf("%-40s '%s'\n",arr[j],extract_ext(arr[j]))

tmp = 1

}

}

return(fn)

}

<pre>

picture.jpg 'jpg'

file.odd_one ''

</pre>

=={{header|C}}==

#include <ctype.h>

#include <string.h>

#include <stdio.h>

 

char* file_ext(const char *string)

{

 

for (char *iter = ext + 1; *iter != '\0'; iter++) {

return (char*) string + strlen(string);

}

 

}

 

int main(void)

{

};

 

}

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<pre>

</pre>

 

{

 

 

 

}

 

=={{header|Emacs Lisp}}==

=>

 

No extension is distinguished from empty extension but an <code>(or ... "")</code> can give <code>""</code> for both if desired

 

 

An Emacs backup <code>~</code> or <code>.~NUM~</code> are not part of the extension, but otherwise any characters are allowed.

 

 

 

 

}

 

for i := len(path) - 1; i >= 0; i-- {

return path[i:]

default:

return ""

 

func main() {

}

}

}

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</pre>

 

=={{header|J}}==

'''Implementation:'''

 

 

Obviously most of the work here is done by the regex implementation ([[wp:Perl Compatible Regular Expressions|pcre]], if that matters - and this particular kind of expression tends to be a bit more concise expressed in [[Perl|perl]] than in J...).

 

'''Alternative non-regex Implementation'''

 

'''Task examples:'''

 

ext each Examples

 

=={{header|jq}}==

 

 

In the first section, a version intended for jq version 1.4 is presented.

 

{{works with|jq| 1.4}}

def alphanumeric: explode | unique

| reduce .[] as $i

rindex(".") as $ix

| if $ix then .[1+$ix:] as $ext

else ""

end

else ""

 

{{works with|jq|1.5}}

 

'''Examples''':

 

Using either version above gives the same results.

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=={{header|Oforth}}==

If extension is not valid, returns null, not "".

Easy to change if "" is required.

 

| i |

s lastIndexOf('.') dup ->i ifNull: [ null return ]

s extract(i, s size)

 

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<pre>

</pre>

=={{header|PowerShell}}==

$ext = [System.IO.Path]::GetExtension($file)

if (-not [String]::IsNullOrEmpty($ext)) {

$ext

}

<b>Output:</b>

 

 

</pre>

 

=={{header|Python}}==

 

 

 

=={{header|Racket}}==

 

;; Note that for a real implementation, Racket has a

;; and handles path values so might run into problems with unicode

;; string inputs.

(define (string-extension x)

(cadr (regexp-match #px"(\\.[[:alnum:]]+|)$" x)))

 

 

 

 

 

 

</pre>

 

=={{header|REXX}}==

 

<pre>

</pre>

 

=={{header|sed}}==

 

{{out}}

 

 

</pre>

 

=={{header|Tcl}}==

Tcl's built in [http://wiki.tcl.tk/10072 file extension] command already almost knows how to do this, except it accepts any character after the dot. Just for fun, we'll enhance the builtin with a new subcommand with the limitation specified for this problem.

 

if {![uplevel 1 [list expr $expr]]} {

set msg "{$expr}"

proc file_ext {file} {

set res ""

return $res

}

# and a test:

foreach {file ext} {

} {

set res ""

assert {[file ext $file] eq $ext}

 

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<pre>

</pre>

ext

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