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Website Programming in PHP / MYSQL
Passing by Reference
You can pass variable to function by reference, so that function could modify its arguments. The syntax is as follows:
<?php
function foo(&$var)
{
$var++;
}
$a=5;
foo($a);
// $a is 6 here
?>
The following things can be passed by reference:
- Variable, i.e. foo($a)
- New statement, i.e. foo(new foobar())
-
Reference, returned from a function, i.e.:
See also explanations about returning by reference.<?php
function &bar()
{
$a = 5;
return $a;
}
foo(bar());
?>
Any other expression should not be passed by reference, as the result is undefined. For example, the following examples of passing by reference are invalid:
<?php
function bar() // Note the missing &
{
$a = 5;
return $a;
}
foo(bar()); // Produces fatal error since PHP 5.0.5
foo($a = 5); // Expression, not variable
foo(5); // Produces fatal error
?>
