php check if variable exists
snippet in php

isset() in php

user2805

<?php

  $a = 0;
// True because $a is set
if (isset($a)) {
  echo 
  "Variable 'a' is set.<br>";
}

$b = null;
// False because $b is 
  NULL
if (isset($b)) {
  echo "Variable 'b' is set.";
}
?>
 

isset in php

user8793

/**
 * Returns a bool (true or false)
 */
isset($x);
/**
 * Examples
 */
$x = 'myValue';
if(isset($x)){
	echo 'x is set';
}
/**
 * this will echo out 'x is set'
 */


$x = null;
if(isset($x)){
	echo 'x is set';
}
/**
 * This will NOT echo out 'x is set'
 */


if(isset($y)){
 	echo 'y is set'; 
}
/**
 * This will NOT echo out 'y is set'
 */

if exist php

user4067

if (isset($var)) {
  // Code here
}

php check if variable exists

user7743


<?php

  $a = 0;
// True because $a is set
if (isset($a)) {
  echo 
  "Variable 'a' is set.<br>";
}

$b = null;
// False because $b is 
  NULL
if (isset($b)) {
  echo "Variable 'b' is set.";
}
?>
 

what is isset in php

user6060

The isset() function checks whether a variable is set, which means that it has to be declared and is not NULL.

This function returns true if the variable exists and is not NULL, otherwise it returns false.