<?php
$chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890';
$length = 5;
$numChars = strlen($chars);
$numberOfStringsGenerated = 50000;
print "numStringsGenerated: " . $numberOfStringsGenerated . "\n";
print "numChars: " . $numChars . "\n";
print "lengthOfString: " . $length . "\n";
$totalPerms = 1;
for ($ii=0; $ii<$length; $ii++) {
$totalPerms *= $numChars - $ii;
}
print "totalPerms: " . $totalPerms . "\n";
$totalProbablity = 1;
for ($ii=0; $ii< $numberOfStringsGenerated; $ii++) {
$totalProbablity *= ($totalPerms - $ii)/$totalPerms;
}
print "Probablity: ";
print 1 - $totalProbablity . "\n";