[ OCR J277 ERL ]

IF Statements

Here is the standard syntax for an IF block in ERL.

• Start with if [condition] then
• Add optional elseif [condition] then
• Add an optional else
• Always close with endif

ageStr = input("Age?")
age = int(ageStr)

if age >= 18 then
    print("You can vote")
elseif age == 17 then
    print("You can vote next year")
else
    print("Too young to vote")
endif

Exercise: Grade Calculator

Ask the user for their test score (out of 100). Use an IF statement to print out their grade.

• 80 or higher: Grade A
• 60 or higher: Grade B
• 40 or higher: Grade C
• Below 40: Fail

Logical Operators

You can combine conditions using AND and OR. You can reverse a condition with NOT.

if score > 50 AND attendance > 90 then
    print("Pass")
endif

Exercise: Weekend Checker

Use input to ask "What day is it?". Use an IF statement with the OR operator to print "Weekend" if the day is "Saturday" or "Sunday". Otherwise print "Weekday".

SWITCH / CASE

When you have many possible exact values for a single variable, switch is cleaner than multiple if/elseif blocks.

switch day:
    case "Sat":
        print("Weekend!")
    case "Sun":
        print("Weekend!")
    default:
        print("Weekday")
endswitch

Exercise: Switch Menu

Ask the user to enter a number (1, 2, or 3). Use a switch statement: if 1 print "New Game", if 2 print "Load Game", if 3 print "Quit", and for default print "Invalid choice".