IntlChar::isalnum() function in PHP

The IntlChar::isalnum() function is used to check whether a given input character is alphanumeric or not. An alphanumeric character is either a digit (0-9) or a letter (A-Z, a-z).

Syntax

bool IntlChar::isalnum(mixed $codepoint)

Parameters

• codepoint − An integer value or a single character encoded as a UTF-8 string to check.

Return Value

The IntlChar::isalnum() function returns TRUE if the codepoint is an alphanumeric character, FALSE otherwise, or NULL on failure.

Example 1

The following example demonstrates checking various characters ?

<?php
    var_dump(IntlChar::isalnum("A"));
    echo "<br>";
    var_dump(IntlChar::isalnum("5"));
    echo "<br>";
    var_dump(IntlChar::isalnum("$"));
    echo "<br>";
    var_dump(IntlChar::isalnum("z"));
    echo "<br>";
    var_dump(IntlChar::isalnum("0"));
?>

bool(true)
bool(true)
bool(false)
bool(true)
bool(true)

Example 2

Testing with Unicode codepoints and special characters ?

<?php
    var_dump(IntlChar::isalnum("#"));
    echo "<br>";
    var_dump(IntlChar::isalnum("1"));
    echo "<br>";
    var_dump(IntlChar::isalnum(65)); // ASCII code for 'A'
    echo "<br>";
    var_dump(IntlChar::isalnum(48)); // ASCII code for '0'
?>

bool(false)
bool(true)
bool(true)
bool(true)

Key Points

• The function only works with single characters, not strings

• Returns NULL when passed multi-character strings

• Accepts both character literals and Unicode codepoints as integers

• Part of the PHP Intl extension for internationalization support

Conclusion

The IntlChar::isalnum() function provides a reliable way to check if a single character is alphanumeric. It's particularly useful for input validation and character classification in internationalized applications.