In php how would I generate a fixed number from a string within a certain value range

Question

Let's say I have a database of 100,000 more or less random strings and I want to generate a number from each string between 1 and 500.

My method should always generate the same number (given the same string) and it should be an even distribution of numbers from 1 to 500.

Any ideas?

Use a CRC (PHP's crc32() function - php.net/manual/en/function.crc32.php), then adjust the result to fit your range — Mark Baker
– Mark Baker, Commented Mar 21, 2013 at 9:40

Salman Arshad · Accepted Answer · 2013-03-21 18:03:25Z

1

Seems like you need a hashing function. You can use crc32 and modulus operator:

echo abs(crc32("hello world")) % 500 + 1;

edited Mar 21, 2013 at 18:03

answered Mar 21, 2013 at 9:46

Salman Arshad

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1 Comment

Søren Beck Jensen Over a year ago

Please note that crc32() returns a signed integer and thus it can be -1234567. For use in my case adding abs() around the crc32() function did the trick

dendini · Accepted Answer · 2014-02-11 15:36:19Z

0

You could also use something like:

function string_to_decimal($hex_str)
{
    $arr = str_split($hex_str, 4);
    foreach ($arr as $grp) {
        $dec[] = str_pad(hexdec($grp), 5, '0', STR_PAD_LEFT);
    }
    return implode('', $dec);
}

answered Feb 11, 2014 at 15:36

dendini

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