PHP Variable Scope in Functions

Variables declared outside of functions and classes are global. global variables are available else where in the script.

Function variables are self-contained and do not affect variables in the main script.

Variables from the main script are not implicitly made available inside functions.

Take a look at this example:


<?PHP//from   ww  w  . jav  a 2 s .  co m
function foo() { 
   $bar = "java2s.com"; 
} 
$bar = "PHP"; 
foo(); 
print $bar; 
?>

The code above generates the following result.

Execution of the script starts at the $bar = "PHP" line, and then calls the foo() function.

foo() sets $bar to java2s.com, then returns control to the main script where $bar is printed out.

Function foo() is called, and, having no knowledge that a $bar variable exists in the global scope, creates a $bar variable in its local scope.

Once the function ends, all local scopes are gone, leaving the original $bar variable intact.