Conditional Statements

Conditional Statements allow us to control the flow of our program execution. If the code statements only executed one after the other until the end of a function, the functionality would be very limited.

Once upon a time, flow-charts were popular (maybe they still are?) where we could design our program flow with decision nodes to decide which branch to go down. Typically, we would test a condition for true or false and branch accordingly.

In a game, we are likely to have simple true/false conditions to test or, a more complex state with several possibilities.

The basic conditional statement uses the if / else / elif syntax. We use indentation to define the levels for how deep into the if structure we are. Here are some GDScript code examples:

extends Node2D

func _ready():
	var n = 6
	
	# Inline 'if' statement
	if n == 6: print("n is equal to six")
	
	n = 4
	# Regular 'if' statement 
	if n == 4:
		print("n is equal to four")
	
	# 'else/if' statement
	if n == 6:
		print("n is equal to six")
	else:
		print("n is not equal to six")
	
	# Messy indented 'else/if' statement
	if n == 6:
		print("n is equal to six")
	else:
		if n < 6:
			print("n is less than six")
		else:
			print("n is greater than six")
	
	n = 8
	# Tidier 'else/if' statement using 'elif'
	if n == 6:
		print("n is equal to six")
	elif n < 6:
		print("n is less than six")
	else:
        print("n is greater than six")

In the above code, you can see how indentation can get messy where there is more than one if test, so elif may be used to make the code tidier.

Match Statement

In other programming languages, the switch statement is commonly provided to allow for conditional branching based on multiple cases of the test value. GDScript provides a powerful alternative Match statement.

This is explained very well in the official docs, so please follow the above link to find out about it.

Our game state is likely to be in one of many states which may be evaluated by a Match statement to decide which code needs to be executed to process the current game play.

Ternary-if Expressions

This is a handy one-liner to assign a value to a variable based on a condition.

var x = [value] if [expression] else [value]

Code example:

var paid = false
var strength = 9.9 if paid else 1.0
print("Strength = ", strength)

The next topic is GDScript Looping

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