function scope


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.


	      	<?php
			function foo() { 
			   $bar = "studentsempire"; 
			} 
			$bar = "PHP"; 
			foo(); 
			print $bar; 
			?>
	      

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


PHP Global Variables


A global variable can be accessed anywhere in your script, whether inside or outside a function.


In PHP, all variables created outside a function are, in a sense, global in that they can be accessed by any other code in the script that's not inside a function.


To use such a variable inside a function, write the word global followed by the variable name inside the function ' s code block.


		  	<?php
	         $myGlobal = "Hello there!"; 

	         function hello() { 
	            global $myGlobal; 
	            echo "$myGlobal\n"; 
	         } 

	         hello(); // Displays "Hello there!"  
			?>
		  


		  	<?php
	         function setup() { 
	           global $myGlobal; 
	           $myGlobal = "Hello there!"; 
	         } 

	         function hello() { 
	           global $myGlobal; 
	           echo "$myGlobal\n"; 
	         } 

	         setup(); 
	         hello(); // Displays "Hello there!"   
			?>
		  

The $GLOBALS array can access global variables within functions. All variables declared in the global scope are in the $GLOBALS array, which you can access anywhere in the script. Here is a demonstration:


		  	<?php
			function foo() { 
			   $GLOBALS['bar'] = "studentsempire.com"; 
			} 

			$bar = "PHP"; 
			foo(); 
			print $bar; 
			?>
		  

We can also declare more than one global variable at once on the same line, just separate the variables using commas:


		  	function myFunction() { 
			  global $oneGlobal, $anotherGlobal; 
			}   
		  

Be careful with global variables. If you modify the value of a global variable in many different places within your application, it can make it hard to debug your code.





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