Arithmetic Shortcuts

Games often update a variable from its own value: add points to a score, remove hp after a hit.

var score := 10
score = score + 5 # score holds 15

The shortcut += does the same with less code:

var score := 10
score += 5 # score holds 15

Every arithmetic operator has a shortcut:

• += adds: score += 5
• -= subtracts: hp -= 3
• *= multiplies: damage *= 2
• /= divides: speed /= 2
• %= keeps the remainder: turn %= 4
• **= raises to a power: size **= 2

The rules of each operator still apply. When hp holds the integer 10, hp /= 4 drops the decimal part and hp becomes 2.

+= also works on strings, where it adds text to the end:

var greeting := "Hero"
greeting += "!"
print(greeting) # Hero!