Ctype 函数
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ctype_alnum

(PHP 4 >= 4.0.4, PHP 5)

ctype_alnum — Check for alphanumeric character(s)

说明

bool ctype_alnum ( string $text )

Checks if all of the characters in the provided string, text, are alphanumeric. In the standard C locale letters are just [A-Za-z].

参数

text

The tested string.

返回值

Returns TRUE if every character in text is either a letter or a digit, FALSE otherwise.

范例

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";
    }
}
?>

以上例程会输出：

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

注释

Note:

如果给出一个 -128 到 255 之间(含)的整数, 将会被解释为该值对应的ASCII字符 (负值将加上 256 以支持扩展ASCII字符). 其它整数将会被解释为该值对应的十进制字符串.

参见

Ctype 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: Check for alphanumeric character(s)

用户评论:

Rory (07-Dec-2009 12:42)

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

Josip Rodin (12-Aug-2009 05:13)

There doesn't actually seem to be a performance loss compared to using regexes. For example:

<?php        
$sUser = 'my_username01';

$time_start1 = microtime(true);
$aValid = array('-', '_');
$ret1 = ctype_alnum(str_replace($aValid, '', $sUser));
$time_end1 = microtime(true);
$time1 = $time_end1 - $time_start1;
printf("Checked it with ctype_alnum and got %d in %.10f seconds\n", print_r($ret1, true), $time1);

$time_start2 = microtime(true);
$ret2 = preg_match('/^[\w-]+$/', $sUser);
$time_end2 = microtime(true);
$time2 = $time_end2 - $time_start2;
printf("Checked it with preg_match  and got %d in %.10f seconds\n", print_r($ret2, true), $time2);

?>

This returns:

% time php ctype_alnum.php
Checked it with ctype_alnum and got 1 in 0.0000379086 seconds
Checked it with preg_match  and got 1 in 0.0001120567 seconds
php ctype_alnum.php  0,01s user 0,01s system 84% cpu 0,024 total
% time php ctype_alnum.php
Checked it with ctype_alnum and got 1 in 0.0000400543 seconds
Checked it with preg_match  and got 1 in 0.0001108646 seconds
php ctype_alnum.php  0,00s user 0,02s system 98% cpu 0,024 total
% time php ctype_alnum.php
Checked it with ctype_alnum and got 1 in 0.0000391006 seconds
Checked it with preg_match  and got 1 in 0.0001142025 seconds
php ctype_alnum.php  0,02s user 0,01s system 98% cpu 0,024 total

ctype_alnum() seems to be consistently faster. I'm guessing that the preg engine initialization induces a bit of overhead.

thinice at gmail dot com (22-Jul-2009 10:46)

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.';
}
?>