PHP/Language Basics/Variable Reference

$b is assigned a copy of $a, and in the second part, $b is assigned a reference to $a.

   <source lang="html4strict">

<?php $a = 5; $b = $a; $a = 7; echo "\$a = $a and \$b = $b\n";

$a = 5; $b = &$a; $a = 7; echo "\$a = $a and \$b = $b\n"; ?>

 </source>
   
  

Create a reference to a variable with the name of the constant"s value.

   <source lang="html4strict">

<?php define("CONST_A", "test"); ${CONST_A} = 27; echo "\$test = $test\n"; ?>

 </source>
   
  

Only named variables may be assigned by reference.

   <source lang="html4strict">

<?php

   $foo = 25;
   $bar = &$foo; // This is a valid assignment.
   
   function test() {
       return 25;
   }
   $bar = &test(); // Invalid.

?>

 </source>
   
  

& operator creates a reference

   <source lang="html4strict">

<?php $a = 5; $b = $a; $a = 7; echo "\$a = $a and \$b = $b\n"; $a = 5; $b = &$a; $a = 7; echo "\$a = $a and \$b = $b\n"; ?>

 </source>
   
  

Passing arrays by reference

   <source lang="html4strict">

<?

   function load_member_data($ID, &$member) {
           $member["Name"] = "Bob";
           return true;
   }
   $ID = 1;
   $result = load_member_data($ID, $member);
   if ($result) {
           print "Member {$member["Name"]} loaded successfully.\n";
   } else {
           print "Failed to load member #$ID.\n";
   }

?>

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Passing by Reference in PHP

   <source lang="html4strict">

<?php

   function reference_test($var, &$result, &$result2) {
       $result = "This is return value #1";
       $result2 = "You entered $var as your parameter";
       return 42;
   }
   $res = reference_test(10, &$res1, &$res2);
   echo "The value of \$res is "$res"
";
   echo "The value of \$res1 is "$res1"
";
   echo "The value of \$res2 is "$res2"
";

?>

 </source>