ctype_xdigit()

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

检测字符串是否只包含十六进制字符

说明

ctype_xdigit(string $text): bool

检查string和$text里面的字符是不是都是十六进制字符串。

参数

$text: 需要被测试的字符串。

返回值

如果$text里面的每个字符都是十六进制字符。也就是只能包含十进制的树枝和[A-Fa-f]的字母。否则，返回FALSE。

范例

一个ctype_xdigit()的例子

<?php
$strings = array('AB10BC99', 'AR1012', 'ab12bc99');
foreach ($strings as $testcase) {
    if (ctype_xdigit($testcase)) {
        echo "The string $testcase consists of all hexadecimal digits.\n";
    } else {
        echo "The string $testcase does not consist of all hexadecimal digits.\n";
    }
}
?>

以上例程会输出：

The string AB10BC99 consists of all hexadecimal digits.
The string AR1012 does not consist of all hexadecimal digits.
The string ab12bc99 consists of all hexadecimal 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_digit()做纯数字检测

This function shows its usefulness on a web site where a user is asked to entered a hexidecimal color code for a color. To prevent breaking W3C standard and having them enter in "neon-green" or the wrong type of code like 355511235.
In conjunction with strlen() you could create a function like this:
function check_valid_colorhex($colorCode) {
  // If user accidentally passed along the # sign, strip it off
  $colorCode = ltrim($colorCode, '#');
  if (
     ctype_xdigit($colorCode) &&
     (strlen($colorCode) == 6 || strlen($colorCode) == 3))
        return true;
  else return false;
}