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ctype_xdigit

(PHP 4 >= 4.0.4, PHP 5)

ctype_xdigit --  Check for character(s) representing a hexadecimal digit

说明

bool ctype_xdigit ( string text )

Checks if all of the characters in the provided string, text, are hexadecimal 'digits'.

参数

text

The tested string.

返回值

Returns TRUE if every character in text is a hexadecimal 'digit', that is a decimal digit or a character from [A-Fa-f] , FALSE otherwise.

范例

例子 1. A ctype_xdigit() example

<?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";
    }
}
?>

上例将输出：

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.

参见

ctype_digit()


add a note add a note User Contributed Notes
tom at hgmail dot com
15-Jan-2006 04:36
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;
}
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ctype_upper上一级Classes/Objects 类／对象函数