How to check for alphabets in php?

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

ctype_alpha — Check for alphabetic character(s)

Description

ctype_alpha(mixed $text): bool

Parameters

The tested string.

Note:

If an int between -128 and 255 inclusive is provided, it is interpreted as the ASCII value of a single character (negative values have 256 added in order to allow characters in the Extended ASCII range). Any other integer is interpreted as a string containing the decimal digits of the integer.

Warning

As of PHP 8.1.0, passing a non-string argument is deprecated. In the future, the argument will be interpreted as a string instead of an ASCII codepoint. Depending on the intended behavior, the argument should either be cast to string or an explicit call to chr() should be made.

Return Values

Returns true if every character in text is a letter from the current locale, false otherwise. When called with an empty string the result will always be false.

Examples

Example #1 A ctype_alpha() example (using the default locale)

$strings = array('KjgWZC', 'arf12');
foreach ($strings as $testcase) {
    if (ctype_alpha($testcase)) {
        echo "The string $testcase consists of all letters.\n";
    } else {
        echo "The string $testcase does not consist of all letters.\n";
    }
}
?>

The above example will output:

The string KjgWZC consists of all letters.
The string arf12 does not consist of all letters.

See Also

• ctype_upper() - Check for uppercase character(s)
• ctype_lower() - Check for lowercase character(s)
• setlocale() - Set locale information

Tyrunur ¶

13 years ago

It works if you set the locale correctly:

setLocale

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

ctype_alnum — Check for alphanumeric character(s)

Description

ctype_alnum(mixed $text): bool

Parameters

The tested string.

Note:

If an int between -128 and 255 inclusive is provided, it is interpreted as the ASCII value of a single character (negative values have 256 added in order to allow characters in the Extended ASCII range). Any other integer is interpreted as a string containing the decimal digits of the integer.

Warning

As of PHP 8.1.0, passing a non-string argument is deprecated. In the future, the argument will be interpreted as a string instead of an ASCII codepoint. Depending on the intended behavior, the argument should either be cast to string or an explicit call to chr() should be made.

Return Values

Returns true if every character in text is either a letter or a digit, false otherwise. When called with an empty string the result will always be false.

Examples

Example #1 A ctype_alnum() example (using the default locale)

$strings = array('AbCd1zyZ9', 'foo!#$bar');
foreach ($strings as $testcase) {
    if (ctype_alnum($testcase)) {
        echo "The string $testcase consists of all letters or digits.\n";
    } else {
        echo "The string $testcase does not consist of all letters or digits.\n";
    }
}
?>

The above example will output:

The string AbCd1zyZ9 consists of all letters or digits.
The string foo!#$bar does not consist of all letters or digits.

See Also

• ctype_alpha() - Check for alphabetic character(s)
• ctype_digit() - Check for numeric character(s)
• setlocale() - Set locale information

thinice at gmail dot com ¶

13 years ago

ctype_alnum() is a godsend for quick and easy username/data filtering when used in conjunction with str_replace().

Let's say your usernames have dash(-) and underscore(_) allowable and alphanumeric digits as well.

Instead of a regex you can trade a bit of performance for simplicity:

$sUser = 'my_username01';
$aValid = array('-', '_');

if(!

marcelocamargo at linuxmail dot org ¶

6 years ago

It is also important to note that the behavior of `ctype_alnum` differs according to the operating system. For UNIX-based operating system, if you pass a value that is not a string (or an overloaded object), independently of the value, it will always result in false. However, if we do the same on Windows, using, for example, -1 as literal (a minus and a number greater than 0), we'll have true as result.

(ctype_alnum(-1));
// UNIX: bool(false)
// Windows: bool(true)

Anonymous ¶

9 years ago

Quicktip: If ctype is not enabled by default on your server, replace ctype_alnum($var) with preg_match('/^[a-zA-Z0-9]+$/', $var).

Rory ¶

12 years ago

Just for the record, Gentoo doesn't include this function by default. You'll have to recompile PHP with the "ctype" USE flag.