CODEWITHSUNDEEP
phpcodeigniterrandom
DOE
DOE

Reputation: 53

Generate very Uniquer number in PHP - CodeIgniter

I am developing a very big application where i want to create very very unique random numbers which will never ever match the previous records.Here is my code

function random_number($maxlength = 17) {
    $chary = array("a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",
                    "0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
                    "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z");
    $return_str = "";
    for ( $x=0; $x<=$maxlength; $x++ ) {
        $return_str .= $chary[rand(0, count($chary))];
    }
    return $return_str;
}

Now it works fine but some time it give me error

Notice: Undefined offset: 62 in test.php on line 8

Where line 8 is

$return_str .= $chary[rand(0, count($chary))];

Can anyone fix this for me?

Secondly is there any function in CI for random numbers?

Upvotes: 1

Views: 6412

Answers (3)

Scott Arciszewski
Scott Arciszewski

Reputation: 34123

I am developing a very big application where i want to create very very unique random numbers which will never ever match the previous records

Then don't use any of these functions:

  • rand()
  • mt_rand()
  • lcg_value()
  • str_shuffle()
  • uniqid()

They're all weak. Instead, you want random_int(). Otherwise, the accepted answer is... acceptable.

Upvotes: 0

Sergey Shcherbin
Sergey Shcherbin

Reputation: 401

Try uniqid it is standard php function and you dont need to invent your own bicycle. There is downsides in it but its other topic.

Upvotes: 0

Rajdeep Paul
Rajdeep Paul

Reputation: 16963

From the manual,

int rand ( int $min , int $max )

If called without the optional min, max arguments rand() returns a pseudo-random integer between 0 and getrandmax(). If you want a random number between 5 and 15 (inclusive), for example, use rand(5, 15).

So you have to change the range parameter in rand() function, from rand(0, count($chary)) to rand(0, count($chary)-1)

function random_number($maxlength = 17) {
    $chary = array("a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",
                    "0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
                    "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z");
    $return_str = "";
    for ( $x=0; $x<=$maxlength; $x++ ) {
        $return_str .= $chary[rand(0, count($chary)-1)];
    }
    return $return_str;
}

Upvotes: 1

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