PHP – How to check if a variable is set?

In this tutorial, you shall learn how to check if a variable is set in PHP using isset() function, with the help of example programs.

PHP – Check if variable is set

To check if a variable is set in PHP, pass the variable as argument to isset() function. The function returns a Boolean value of true if the variable is set, or else it returns false.

Syntax

The syntax to use isset() function to check if variable $x is a set or not is

isset($x)

Example

In the following program, we take an integer value in variable $x, and programmatically check if this variable is set or not.

PHP Program

<?php
  $x = 48;
  if ( isset($x) ) {
    echo "variable x is set.";
  } else {
    echo "variable x is not set.";
  }
?>

Output

Now, let us check if variable $y is set or not. In the following program, we have not taken any variable named $y. Therefore, else block must execute.

PHP Program

<?php
  if ( isset($y) ) {
    echo "variable y is set.";
  } else {
    echo "variable y is not set.";
  }
?>

Output

Conclusion

In this PHP Tutorial, we learned how to check if a variable is set or not, using isset() function.