PHP Introduction | Functions | empty - Check Whether a Variable Is Empty

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You can use empty to check whether a variable is empty. It is available from PHP 4.

Syntax

empty( $var )

Checks whether $var is empty. It returns TRUE if it is empty, and FALSE if it is not empty.

The following are considered empty.

  • "" (empty string)
  • 0 (integer 0)
  • "0" (string 0)
  • NULL
  • FALSE
  • array() (empty array)
  • var $var; (a variable declared without a value inside a class)

Example

<!DOCTYPE html>
<html lang="ko">
  <head>
    <meta charset="utf-8">
    <title>Coding Factory</title>
    <style>
      p {
        font-family: "Times New Roman";
        font-style: italic;
        font-size: 1.3em;
      }
    </style>
  </head>
  <body>
    <?php
      $var1 = NULL;
      $var2 = "";
      $var3 = "0";
      $var4 = "Lorem";
      if ( empty( $var1 ) ) {
        echo "<p>var1 is empty.</p>";
      } else {
        echo "<p>var1 is not empty.</p>";
      };
      if ( empty( $var2 ) ) {
        echo "<p>var2 is empty.</p>";
      } else {
        echo "<p>var2 is not empty.</p>";
      };
      if ( empty( $var3 ) ) {
        echo "<p>var3 is empty.</p>";
      } else {
        echo "<p>var3 is not empty.</p>";
      };
      if ( empty( $var4 ) ) {
        echo "<p>var4 is empty.</p>";
      } else {
        echo "<p>var4 is not empty.</p>";
      };
    ?>
  </body>
</html>