(PHP 4 >= 4.0.4, PHP 5)
ctype_xdigit — Check for character(s) representing a hexadecimal digit
Checks if all of the characters in the provided string, text, are hexadecimal 'digits'.
The tested string.
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.
Example #1 A ctype_xdigit() example 以上例程会输出：
<?php
$strings = array('AB10BC99', 'AR1012', 'ab12bc99');
foreach ($strings as $testcase) {
if (ctype_xdigit($testcase)) {
echo "The string $testcase consists of all hexadecimal digits.
";
} else {
echo "The string $testcase does not consist of all hexadecimal digits.
";
}
}
?>
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:
If an integer between -128 and 255 inclusive is provided, it is interpreted as the ASCII value of a single character (negative values have 256 added in order to allow characters in the Extended ASCII range). Any other integer is interpreted as a string containing the decimal digits of the integer.