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ctype_xdigit — 检测字符串是否只包含十六进制字符
$text
)
检查 string 和 text
里面的字符是不是都是十六进制字符串。
text
需要被测试的字符串。
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
。
Example #1 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 $testcase does not consist of all hexadecimal digits.\n" ;
}
}
?>
以上例程会输出:
The string AB10BC99 consists of all hexadecimal digits. The string AR1012 does not consist of all hexadecimal digits. The string ab12bc99 consists of all hexadecimal digits.
Note:
如果给出一个 -128 到 255 之间(含)的整数, 将会被解释为该值对应的ASCII字符 (负值将加上 256 以支持扩展ASCII字符). 其它整数将会被解释为该值对应的十进制字符串.
[#1] tom at hgmail dot com [2006-01-14 12:36:41]
This function shows its usefulness on a web site where a user is asked to entered a hexidecimal color code for a color. To prevent breaking W3C standard and having them enter in "neon-green" or the wrong type of code like 355511235.
In conjunction with strlen() you could create a function like this:
function check_valid_colorhex($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;
}