view generating random string

Hi Mohammad,

I also see a few errors in this code: the is_int call needs a closing parenthesis and the character check needs to check strlen($characters) and check greater than zero, not less than zero, the return statement needs to be outside the for loop and the function is closed in the wrong place. Here's a corrected version:

<?php
function str_rand($length = 32, $character = '0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM')
{
    // fixed parentheses, added length>0 check and changed to &&s
    if(!(is_int($length) && $length > 0 && strlen($character) > 0))
    {
      return false;
    }

    $character_length = strlen($character) - 1;
    $string ='';

    for($i = $length; $i > 0; $i--){
      $string .= $character[mt_rand(0, $character_length)];
    }

    return $string;
} // closing function here

// call the function and store the result in a variable
$random_string = str_rand();

// spit out the value of the variable to the screen when you load this file
var_dump($random_string);


?>

Here's what the function does, as I read it:

Essentially, the function is meant to choose random characters from the character set provided, and creates a string using those characters. The function then returns the string.

The function, str_rand, takes two arguments; a length, and a string of characters. Both arguments have default values. The length is 32 unless specified otherwise, the string of characters is a string consisting of 0-9, a-z and A-Z.

The function checks to make sure the two arguments were supplied correctly (the length should be an integer, and the character set should have at least one character in it), and if not it returns false.

If the check is passed, an empty $string is initialized, and a for loop adds a random character from the character string provided (or the default char string) to the $string. The line $character[mt_rand(0, $character_length)] picks a random integer between 0 and the length of the character string minus one (since a string is a 0-based array of characters) and indexes into the string to pull out that character. This loop runs until the string is the length provided in the function call (32 characters long by default).

Then the function returns the string that's been built up.

To display the result on the screen, you need to call the function and then var_dump it, or use it some other way to display it. I've used var_dump in my example above.

Let me know if you have any other specific questions!

Cheers,

-Greg

P.S. - A quick word about spacing. PHP doesn't care about this, per se, but it's a best practice to keep your spacing "balanced" around mathematical operators. In almost every instance of a mathematical operator you put a space before but not after it. That makes it harder to read. Either don't use spaces or do, but keep them balanced. Personally I strongly prefer spaces.

$var = 2 + 5; for example, not $var =2 +5.

Some languages actually enforce this as a rule (though as I said PHP is not one of them).

I have looked at your code more and have some more comments but would like to refine them. What are you trying to accomplish with this code?