IF-Statements... Your Ever Lasting Problem Explained

I was talking with someone on MSN, who explained me that she had problems with if-statements. That it was like learning maths. I don't have much problems with it, but others may have.

So today, let's talk about the basics of if-statements.

What IS it?
They are the possibility to check variables (that's just one thing) against another variable. Or value against variable (or otherwise).

An example can be a simple dice. I first use the rand() function to produce a random number between 1 and 6. Then, if the dice returns 5, I output something. Basically, this is the #5 Dice game (doesn't exists, I hope?). When the dice returns 5, the player wins, else the player loses.

<?php
$dice = rand(1,6);
if($dice == 5)
{
echo "You won!";
}else{
echo "You loose!";
}
?>

Fairly simple... right? Note that if you use $dice = 5, you actually assign the number 5 to the variable $dice, which will usually always return to true, meaning that it looks like the dice always returns 5 in this case!

What's more?
What if you have the same dice, but now if the dice is 4,5,6 (basically, any number higher than 3), the player wins, else looses. This can be done in two different ways. Either check whether the number is higher than 3, or whether the number is 4 or higher. When doing higher than 3:

if($dice > 3)

When doing 4 or higher:

if($dice >= 4)

This isn't acracadabra, right!?
Let's move on! The type comparing operator, === and !==. This will check if the types of the two values match, in addition to the value. For example:

<?php
if((int) 5 == "5")
{
echo "Exactly the same!";
}
if((int) 5 === "5")
{
echo "Exactly the same!";
}
?>

You would guess that 5 is still 5 right? But the second if-statements says, hey, the first one is an integer, the other one is a string!

Now, on to the next example: the dice must NOT return 5, or the player will loose.

if($dice != 5)
{
echo "You won!";
}

And another example, the dice must be either 1 or 6, in order for the player to win.

if($dice == 1 || $dice == 6)
{
echo "You won";
}

As you can see, || means OR. If you want to do AND, you do &&. With the OR statements, both sides of the || can be true, with the AND statement, both must be. We also have the exclusive or, or XOR. Then either one must be true, but NOT both. For example, we have two dices. One of them must be the number 1, but NOT BOTH!

<?php
$dice_one = rand(1,6);
$dice_two = rand(1,6);
if($dice_one == 1 ^ $dice_two == 1)
{
echo "You won!";
}
?>

I think that's enough brain-cracking for today.

Good luck using this ;)