giving players items with chances

I want to make players get 20% chance of getting diamonds and 80% chance of getting dirt. but i tried

PHP:

rand(1,100);
if($rand =< 20){
20%
}elseif($rand > 20){
80%
}


but they said this one is bad

 

This has a 1% (yeah, no "pseudo random") chance of returning any number between 1 and 100.

PHP:

$rand = rand(1, 100);


So this will have a 20% chance of returning true.

PHP:

if($rand <= 20){
    return true;
}
return false;


 

What you can do is recalculate a random number every time. That makes it a little more random.

PHP:

if(rand(1, 100) <= 20){
}elseif(rand(1, 100) <= 80){
}


 

PHP:

function chance(int $chance, callable $high, callable $low){
    $rand = rand(1, 100);
    return $rand > $chance ? $low() : $high();
}

chance(20, function(){
    echo "give the players diamonds";
}, function(){
    echo "give em dirt";
});

 

PHP:

$chance = rand(0, 2);
switch($chance) {
  case 0:

  break;
  case 1:

  break;
  case 2:

  break;

}

 

That would be 33.3% chance.
20 and 80 percent would be rand(1, 5) so each number has a 20% chance of being called (20% = rand(1, 5) === 1, 80% = rand(1, 5) !== 1).