Global Variable

Global Variable

1.A variable has a global scope if it is defined outside of any function.
2. Global variables can be accessed from any part of the program except function.
3.To access a global variable from within a function, use the global keyword.

Example: 1

<?phpfunction echo_ip(){
  $user_ip=$_SERVER["REMOTE_ADDR"]; // local scope
  $str="Your IP address is ".$user_ip;
  echo $str;
}echo_ip();?>

Output

Your IP address is ::1 
Here $user_ip is declared local.

Example: 2

<?php
$user_ip=$_SERVER["REMOTE_ADDR"]; // global scopefunction echo_ip(){$str="Your IP address is ".$user_ip;
echo $str;
}echo_ip();?>

Output

Here we don't see any output. Because $user_ip is declared global.

To access $user_ip global variable from within a function, use the global keyword.

Example: 3

<?php
$user_ip=$_SERVER["REMOTE_ADDR"]; // global scopefunction echo_ip(){
  global $user_ip;
  $str="Your IP address is ".$user_ip;
  echo $str;
}echo_ip();?>

Output

Your IP address is ::1 

Example: 4

<?php
$a = 5;$b = 10;
function sum(){
  global $a, $b;
  $b = $a + $b;
}sum();
echo $b;?>

Output

15