(PHP 4 >= 4.0.4, PHP 5)
ctype_alnum — Check for alphanumeric character(s)
Checks if all of the characters in the provided string, text, are alphanumeric. In the standard C locale letters are just [A-Za-z].
The tested string.
Returns TRUE if every character in text is either a letter or a digit, FALSE otherwise.
Example #1 A ctype_alnum() example (using the default locale) 以上例程会输出：
<?php
$strings = array('AbCd1zyZ9', 'foo!#$bar');
foreach ($strings as $testcase) {
if (ctype_alnum($testcase)) {
echo "The string $testcase consists of all letters or digits.
";
} else {
echo "The string $testcase does not consist of all letters or digits.
";
}
}
?>
The string AbCd1zyZ9 consists of all letters or digits.
The string foo!#$bar does not consist of all letters or digits.
Note:
If an integer 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.