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;
}
ctype_xdigit
(PHP 4 >= 4.0.4, PHP 5, PHP 7)
ctype_xdigit — Check for character(s) representing a hexadecimal digit
Descrierea
Checks if all of the characters in the provided string,
text, are hexadecimal 'digits'.
Parametri
-
text -
The tested string.
Notă:
Dacă e furnizat un integer cu valoarea între -128 și 255 inclusiv, el este interpretat ca o valoare ASCII a unui singur caracter (valorilor negative li se adaugă 256 pentru a permite caractere din domeniul ASCII extins). Orice alt întreg este interpretat ca un string conținând cifrele zecimale ale întregului.
Valorile întoarse
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.
Exemple
Example #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";
}
}
?>
Exemplul de mai sus va afișa:
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.
add a note
User Contributed Notes 2 notes
tom at hgmail dot com ¶
18 years ago
Anonymous ¶
1 year ago
this can be used with great results if you wanna check for something like
"Tobias2" whether there is a number at the end of the string. (F.e. courselist with coursenames etc.)
Just substring the last char and put it in the function.
We should be glad about every possibility to cut out these damn regexes from our code. NEVER USE REGEX
