Difference Between These 2 Percent Calculations lol

[Monkuar]

$roll = rand(1, 100);
$failureChance = 100 - $successrate;
if ($roll > $failureChance)
{
    // This is successful.
} 

VS:

$rand = mt_rand(1, 100); 
if ($rand > $successrate) // Success rate is your integer; 87 for 87% for example 
{ 
    // This is a failure. 
} 

Are they both essentially the same? Why the heck is that guy using the $falureChance variable? (Cite from http://www.codingforums.com/showthread.php?t=250281)

 

Edit: also, which one is more professional/correct way?

[kicken]

Are they both essentially the same?

Yes.

 

Why the heck is that guy using the $falureChance variable?

Because the other guy was having a hard time understanding the inverted logic of the other code, so he tried to make it easier to understand by renaming the variable.