If only...

• if statements have the form of:

		if ($garfield == 6) {
			print "Garfield is most definitely six\n";
		}

• The bolded code is the control structure. Everything { between the curly braces } will be executed if the condition ($garfield == 6) is true.

		$popcorn = 10;

		if ($popcorn == 10) { }

		if ($popcorn < 15) { }
		if ($popcorn != 1) { }
		if ($popcorn eq "10") { }
		if ($popcorn = 15) { }			#Huh?

		$behavior = "music";
		if ($behavior eq "music") { }
		if ($behavior = "mon ami") { }	#Same as last odd one...
		if ($behavior =~ /music/) { }   #Huh?
		if (length($behavior == 5) { }  #What?

• And some things it thinks are false:

		if ($popcorn == 5) { }

		if ($popcorn eq "dancing") { }
		if ($behavior ne "music") { }

• So far all of the conditions have been comparisons of some sort: greater than, less than, is equal to, is equivalent to, matches. The exceptions of course were the assignements ($popcorn = 15) and ($behavior = "mon ami"). Why were these true? Consider this: Perl also considers the following condition true:

		if (1) { }  #True!

• And this false:

		if (0) { }  #False!

• Remember: Computers are dumb. For a computer true just means "anything that's not 0" and false means "0". ($popcorn = 15) is true because it's 15, which is not 0. ($behavior = "mon ami") is true because it's "mon ami", which is not 0. However, ($popcorn = 0) would be false, because it's 0.

• else statements:

		$popcorn = 10;

		if ($popcorn == 15) {
			print "Popcorn is 15";

		}

		else {

			print "What?  Popcorn isn't 15??";

		}

• The statements enclosed in the else's curly braces execute if the preceding if's condition evaluates as false. If the if is true, the else does nothing.