Description
string
urlencode ( string str )
Returns a string in which all non-alphanumeric characters except
-_. have been replaced with a percent
(%) sign followed by two hex digits and spaces
encoded as plus (+) signs. It is encoded the
same way that the posted data from a WWW form is encoded, that is
the same way as in
application/x-www-form-urlencoded media type.
This differs from the RFC1738 encoding (see
rawurlencode()) in that for historical
reasons, spaces are encoded as plus (+) signs. This function is
convenient when encoding a string to be used in a query part of
a URL, as a convenient way to pass variables to the next page:
Example 1. urlencode() example
<?php
echo '<a href="mycgi?foo=', urlencode($userinput), '">';
?>
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Note: Be careful about variables that may match HTML entities.
Things like &, © and £ are parsed by the
browser and the actual entity is used instead of the desired
variable name. This is an obvious hassle that the W3C has been
telling people about for years. The reference is here:
http://www.w3.org/TR/html4/appendix/notes.html#h-B.2.2. PHP supports
changing the argument separator to the W3C-suggested semi-colon
through the arg_separator .ini directive. Unfortunately most user
agents do not send form data in this semi-colon separated format.
A more portable way around this is to use & instead of
& as the separator. You don't need to change PHP's
arg_separator for this. Leave it as &, but simply encode
your URLs using htmlentities() or
htmlspecialchars().
Example 2. urlencode() and htmlentities() example
<?php
$query_string = 'foo=' . urlencode($foo) . '&bar=' . urlencode($bar);
echo '<a href="mycgi?' . htmlentities($query_string) . '">';
?>
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See also urldecode(),
htmlentities(),
rawurldecode() and
rawurlencode().
