Create a unique id from letters in php

Tim_Myth 15 years ago

Off the top of my head, I knwo you could use the ord() function to get the ascii value of the characters, then create a number from that, add 1, and create a string with the chr() function. Horribly inefficient though.

If your string will ALWAYS only increment by one letter, and ALWAYS be sequential, you could make it more efficient by just grabbing the last character in the string, getting its ascii value, adding 1 to that, and then convert it back to a character.

[1] reply

hjalte81 15 years ago

Thanks Tim...

Eventually after a lot of searching, I got this to work:

function new_uid($olduid){
$number = base_convert($olduid, 36, 10);
$newnumber = $number+1;
$newuid = base_convert($newnumber, 10, 36);
return $newuid;}
- [1] reply

wayfarer 15 years ago

I did this when I built my own url-minifier (like bit.ly). I started at 'a' and worked my way up to 'Z', after which I went to 'aa', 'ab' .... 'aZ', 'ba', etc. Anyway, here's how I did it:

PHP Code:

  function increment($string) {
    for($i = 0; $i < strlen($string); $i++) {
        if($string[$i] != 'Z') {
            $string[$i] = increment_single($string[$i]);
            break;
        }
        else {
            $string[$i] = increment_single($string[$i]);
            if(strlen($string) == $i + 1) {
                $string .= 'a';
                break;
            }
        }
    }
    return $string;
}
private static function increment_single($char) {
    $dec = ord($char);
    $dec++;
    if($dec == 123) {
        $dec = 48;
    }
    if($dec == 58) {
        $dec = 65;
    }
    if($dec == 91) {
        $dec = 97;
    }
    $char = chr($dec);
    return $char;
}

For some reason I didn't even know that you can increment strings in PHP, though so I'm not exactly sure how that would work instead of this. Anyway, this way is tried and tested, and works exactly how I wanted it to.

SteveJohnson 15 years ago

PHP will increment strings, but it will not change case. IOW, when $a = "z", the next increment will not be "A", but "aa".

herry 15 years ago

A unique site ID can be created in PHP using the uniqid () function. This function has two parameters we can set. The first is the prefix. This is what will be appended to the beginning of each ID. The second is more_entropy. If this is false or not specified it will return 13 characters, if it is true then 23 characters will be returned.