////
// Returns a random code of the specified length, containing characters that are
// equally likely to be any of the digits, uppercase letters, or  lowercase letters.
//
// The default length of 10 provides 839299365868340224 (62^10) possible codes.
//
// NOTE: Do not call wt_srand().  It is handled automatically in PHP 4.2.0 and above
//       and any additional calls are likely to DECREASE the randomness.
////
function randomCode($length=10){
	$retVal = "";
	while(strlen($retVal) < $length){
		$nextChar = mt_rand(0, 61); // 10 digits + 26 uppercase + 26 lowercase = 62 chars
		if(($nextChar >=10) && ($nextChar < 36)){ // uppercase letters
			$nextChar -= 10; // bases the number at 0 instead of 10
			$nextChar = chr($nextChar + 65); // ord('A') == 65
		} else if($nextChar >= 36){ // lowercase letters
			$nextChar -= 36; // bases the number at 0 instead of 36
			$nextChar = chr($nextChar + 97); // ord('a') == 97
		} else { // 0-9
			$nextChar = chr($nextChar + 48); // ord('0') == 48
		}
		$retVal .= $nextChar;
	}
	return $retVal;
}

set_time_limit(0); //turns off the limit
for($cnt=0; $cnt<=61; $cnt++){
	$nextChar = $cnt;
	if(($nextChar >=10) && ($nextChar < 36)){ // uppercase letters
		$nextChar -= 10; // bases the number at 0 instead of 10
		$nextChar = chr($nextChar + 65); // ord('A') == 65
	} else if($nextChar >= 36){ // lowercase letters
		$nextChar -= 36; // bases the number at 0 instead of 36
		$nextChar = chr($nextChar + 97); // ord('a') == 97
	} else { // 0-9
		$nextChar = chr($nextChar + 48); // ord('0') == 48
	}
	print $nextChar;
}

$frequency = array();
$allValues = "0123456789";
$allValues.= "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
$allValues.= "abcdefghijklmnopqrstuvwxyz";
for($cnt=0; $cnt<=count($allValues); $cnt++){
	// initialize all frequencies to 0
	$frequency[substr($allValues,$cnt,1)] = 0;
}
for($cnt=0; $cnt<9000000; $cnt++){
	$frequency[randomCode(1)]++;
}

$minFreq = "";
$maxFreq = "";
foreach ($frequency as $char => $freq) {
	if(($minFreq == "") || ($freq < $minFreq)){
		$minFreq = $freq;
	}
	if(($maxFreq == "") || ($freq > $maxFreq)){
		$maxFreq = $freq;
	}
}

print "Minimum value: $minFreq<br>n";
print "Maximum value: $maxFreq<br>n";
print "Size of Range: ".($maxFreq-$minFreq)."<br>n";
print "<pre>n";
ksort($frequency);
print_r($frequency);
print "</pre>n";