Parsing a string into variables

void parse_str ( string input [, array store])

Previously we looked at a handful of the variables set for you inside the superglobal arrays, of which one was QUERY_STRING. If you recall, this is the literal text sent after the question mark in a HTTP GET request, which means that if the page requested was "mypage.php?foo=bar&bar=baz", QUERY_STRING is set to "foo=bar&bar=baz".

The parse_str() function is designed to take a query string like that one and convert it to variables in the same way that PHP does when variables come in. The difference is that variables parsed using parse_str() are converted to global variables, as opposed to elements inside $_GET. So:

<?php

      if (isset($foo)) {

          print "Foo is $foo<br />";

      } else {

          print "Foo is unset<br />";

      }

  

      parse_str("foo=bar&bar=baz");

  

      if (isset($foo)) {

          print "Foo is $foo<br />";

      } else {

          print "Foo is unset<br />";

      }
 ?>

That will print out "Foo is unset" followed by "Foo is bar", because the call to parse_str() will set $foo to "bar" and $bar to "baz". Optionally, you can pass an array as the second parameter to parse_str(), and it will put the variables into there. That would make the script look like this:

<?php

      $array = array();

  

      if (isset($array['foo'])) {

          print "Foo is {$array['foo']}<br />";

      } else {

          print "Foo is unset<br />";

      }

  

      parse_str("foo=bar&bar=baz", $array);

  

      if (isset($array['foo'])) {

          print "Foo is {$array['foo']}<br />";

      } else {

          print "Foo is unset<br />";

      }
 ?>

That script outputs the same as before, except that the variables found in the query string are placed into $array. As you can see, the variable names are used as keys in the array and their values are used as the array values.

Next chapter: Regular expressions >>

Previous chapter: Complex string printing

Jump to:

Home: Table of Contents