URL encoding
You are encouraged to solve this task according to the task description, using any language you may know.
The task is to provide a function or mechanism to convert a provided string into URL encoding representation.
In URL encoding, special characters, control characters and extended characters are converted into a percent symbol followed by a two digit hexadecimal code, So a space character encodes into %20 within the string.
For the purposes of this task, every character except 0-9, A-Z and a-z requires conversion, so the following characters all require conversion by default:
- ASCII control codes (Character ranges 00-1F hex (0-31 decimal) and 7F (127 decimal).
- ASCII symbols (Character ranges 32-47 decimal (20-2F hex))
- ASCII symbols (Character ranges 58-64 decimal (3A-40 hex))
- ASCII symbols (Character ranges 91-96 decimal (5B-60 hex))
- ASCII symbols (Character ranges 123-126 decimal (7B-7E hex))
- Extended characters with character codes of 128 decimal (80 hex) and above.
Example
The string "http://foo bar/" would be encoded as "http%3A%2F%2Ffoo%20bar%2F".
Variations
- Lowercase escapes are legal, as in "
http%3a%2f%2ffoo%20bar%2f". - Some standards give different rules: RFC 3986, Uniform Resource Identifier (URI): Generic Syntax, section 2.3, says that "-._~" should not be encoded. HTML 5, section 4.10.22.5 URL-encoded form data, says to preserve "-._*", and to encode space " " to "+". The options below provide for utilization of an exception string, enabling preservation (non encoding) of particular characters to meet specific standards.
Options
It is permissible to use an exception string (containing a set of symbols that do not need to be converted). However, this is an optional feature and is not a requirement of this task.
See also
AutoHotkey
<lang AutoHotkey>rawURL = http://foo bar/ SetFormat, Integer, Hex Loop Parse, rawURL
If A_LoopField is not alnum ; not a-zA-Z0-9
encURL .= "%" . SubStr(Asc(A_LoopField), 3)
else encURL .= A_LoopField
MsgBox % encURL</lang>
AWK
<lang awk>BEGIN { for (i = 0; i <= 255; i++) ord[sprintf("%c", i)] = i }
- Encode string with application/x-www-form-urlencoded escapes.
function escape(str, c, len, res) { len = length(str) res = "" for (i = 1; i <= len; i++) { c = substr(str, i, 1); if (c ~ /[0-9A-Za-z]/) #if (c ~ /[-._*0-9A-Za-z]/) res = res c #else if (c == " ") # res = res "+" else res = res "%" sprintf("%02X", ord[c]) } return res }
- Escape every line of input.
{ print escape($0) }</lang>
The array ord[] uses idea from Character codes#AWK.
To follow the rules for HTML 5, uncomment the two lines that convert " " to "+", and use the regular expression that preserves "-._*".
C
<lang c>#include <stdio.h>
- include <ctype.h>
char rfc3986[256] = {0}; char html5[256] = {0};
/* caller responsible for memory */ void encode(unsigned char *s, char *enc, char *tb) { for (; *s; s++) { if (tb[*s]) sprintf(enc, "%c", tb[*s]); else sprintf(enc, "%%%02X", *s); while (*++enc); } }
int main() { unsigned char url[] = "http://foo bar/"; char enc[sizeof(url) * 3];
int i; for (i = 0; i < 256; i++) { rfc3986[i] = isalnum(i)||i == '~'||i == '-'||i == '.'||i == '_' ? i : 0; html5[i] = isalnum(i)||i == '*'||i == '-'||i == '.'||i == '_' ? i : (i == ' ') ? '+' : 0; }
encode(url, enc, rfc3986); puts(enc);
return 0; }</lang>
Go
<lang go>package main
import ( "fmt" "http" "strings" )
func main() { url := http.URLEscape("http://foo bar/") // http.URLEscape replaces ' ' with '+', so: url = strings.Replace(url, "+", "%20", -1) fmt.Println(url) }</lang>
Icon and Unicon
<lang Icon>link hexcvt
procedure main() write("text = ",image(u := "http://foo bar/")) write("encoded = ",image(ue := encodeURL(u))) end
procedure encodeURL(s) #: encode data for inclusion in a URL/URI static en initial { # build lookup table for everything
en := table() every en[c := !string(~(&digits++&letters))] := "%"||hexstring(ord(c),2) every /en[c := !string(&cset)] := c }
every (c := "") ||:= en[!s] # re-encode everything return c end </lang>
Output:
text = "http://foo bar/" encoded = "http%3A%2F%2Ffoo%20bar%2F"
J
J has a urlencode in the gethttp package, but this task requires that all non-alphanumeric characters be encoded.
Here's an implementation that does that:
<lang j>require'strings convert' urlencode=: rplc&((#~2|_1 47 57 64 90 96 122 I.i.@#)a.;"_1'%',.hfd i.#a.)</lang>
Example use:
<lang j> urlencode 'http://foo bar/' http%3A%2F%2Ffoo%20bar%2F</lang>
Java
The built-in URLEncoder in Java converts the space " " into a plus-sign "+" instead of "%20": <lang java>import java.io.UnsupportedEncodingException; import java.net.URLEncoder;
public class Main {
public static void main(String[] args) throws UnsupportedEncodingException
{
String normal = "http://foo bar/";
String encoded = URLEncoder.encode(normal, "utf-8");
System.out.println(encoded);
}
}</lang>
Output:
http%3A%2F%2Ffoo+bar%2F
JavaScript
Confusingly, there are 3 different URI encoding functions in JavaScript: escape(), encodeURI(), and encodeURIComponent(). Each of them encodes a different set of characters. See this article and this article for more information and comparisons.
<lang javascript>var normal = 'http://foo/bar/';
var encoded = encodeURIComponent(normal);</lang>
Objective-C
<lang objc>NSString *normal = @"http://foo bar/"; NSString *encoded = [normal stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; NSLog(@"%@", encoded);</lang>
The Core Foundation function CFURLCreateStringByAddingPercentEscapes() provides more options.
Perl
<lang perl>use URI::Escape;
my $s = 'http://foo/bar/'; print uri_escape($s);</lang>
Use standard CGI module: <lang perl>use 5.10.0; use CGI;
my $s = 'http://foo/bar/'; say $s = CGI::escape($s); say $s = CGI::unescape($s);</lang>
Perl 6
<lang perl6>my $url = 'http://foo bar/';
say $url.subst(/<-[ A..Z a..z 0..9 ]>/, *.ord.fmt("%%%02X"), :g);</lang>
Output:
http%3A%2F%2Ffoo%20bar%2F
PHP
<lang php><?php
$s = 'http://foo/bar/';
$s = rawurlencode($s);
?></lang>
There is also urlencode(), which also encodes spaces as "+" signs
PicoLisp
<lang PicoLisp>(de urlEncodeTooMuch (Str)
(pack
(mapcar
'((C)
(if (or (>= "9" C "0") (>= "Z" (uppc C) "A"))
C
(list '% (hex (char C))) ) )
(chop Str) ) ) )</lang>
Test:
: (urlEncodeTooMuch "http://foo bar/") -> "http%3A%2F%2Ffoo%20bar%2F"
PureBasic
<lang PureBasic>URL$ = URLEncoder("http://foo bar/")</lang>
Python
<lang python>import urllib
s = 'http://foo/bar/'
s = urllib.quote(s)</lang>
There is also urllib.quote_plus(), which also encodes spaces as "+" signs
Ruby
CGI.escape encodes all characters except '-.0-9A-Z_a-z'.
<lang ruby>require 'cgi' puts CGI.escape("http://foo bar/").sub("+", "%20")
- => "http%3A%2F%2Ffoo%20bar%2F"</lang>
URI.encode_www_form_component is a new method from Ruby 1.9.2. It obeys HTML 5 and encodes all characters except '-.0-9A-Z_a-z' and '*'.
<lang ruby>require 'uri' puts URI.encode_www_form_component("http://foo bar/").sub("+", "%20")
- => "http%3A%2F%2Ffoo%20bar%2F"</lang>
Programs should not call URI.escape (alias URI.encode), because it fails to encode some characters. URI.escape is obsolete since Ruby 1.9.2.
Tcl
<lang tcl># Encode all except "unreserved" characters; use UTF-8 for extended chars.
- See http://tools.ietf.org/html/rfc3986 §2.4 and §2.5
proc urlEncode {str} {
set uStr [encoding convertto utf-8 $str]
set chRE {[^-A-Za-z0-9._~\n]}; # Newline is special case!
set replacement {%[format "%02X" [scan "\\\0" "%c"]]}
return [string map {"\n" "%0A"} [subst [regsub -all $chRE $uStr $replacement]]]
}</lang> Demonstrating: <lang tcl>puts [urlEncode "http://foo bar/"]</lang> Output:
http%3A%2F%2Ffoo%20bar%2F%E2%82%AC
TUSCRIPT
<lang tuscript> $$ MODE TUSCRIPT text="http://foo bar/" BUILD S_TABLE spez_char="::>/:</::<%:" spez_char=STRINGS (text,spez_char) LOOP/CLEAR c=spez_char c=ENCODE(c,hex),c=concat("%",c),spez_char=APPEND(spez_char,c) ENDLOOP url_encoded=SUBSTITUTE(text,spez_char,0,0,spez_char) print "text: ", text PRINT "encoded: ", url_encoded </lang> Output:
text: http://foo bar/ encoded: http%3A%2F%2Ffoo%20bar%2F