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:
<?php
$sUser = 'my_username01';
$aValid = array('-', '_');
if(!ctype_alnum(str_replace($aValid, '', $sUser))) {
echo 'Your username is not properly formatted.';
}
?>
ctype_alnum
(PHP 4 >= 4.0.4, PHP 5, PHP 7)
ctype_alnum — Check for alphanumeric character(s)
설명
bool ctype_alnum
( string
$text
)
Checks if all of the characters in the provided string,
text, are alphanumeric.
인수
-
text -
The tested string.
반환값
Returns TRUE if every character in text is either
a letter or a digit, FALSE otherwise.
예제
Example #1 A ctype_alnum() example (using the default locale)
<?php
$strings = array('AbCd1zyZ9', 'foo!#$bar');
foreach ($strings as $testcase) {
if (ctype_alnum($testcase)) {
echo "The string $testcase consists of all letters or digits.\n";
} else {
echo "The string $testcase does not consist of all letters or digits.\n";
}
}
?>
위 예제의 출력:
The string AbCd1zyZ9 consists of all letters or digits. The string foo!#$bar does not consist of all letters or digits.
주의
Note:
-128이상 255이하의 integer를 지정할 경우, 한 문자의 ASCII 값으로 해석합니다. (음수는 256이 더해져 확장 ASCII 영역의 문자가 됩니다) 그 외의 정수는 그 정수를 표현하는 10진 문자열로 해석합니다.
참고
- ctype_alpha() - Check for alphabetic character(s)
- ctype_digit() - Check for numeric character(s)
- setlocale() - Set locale information
add a note
User Contributed Notes 4 notes
thinice at gmail dot com ¶
15 years ago
Anonymous ¶
11 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).
marcelocamargo at linuxmail dot org ¶
8 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.
<?php var_dump(ctype_alnum(-1));
// UNIX: bool(false)
// Windows: bool(true)
