Conditionals

Conditionals allow your program to make decisions and execute different code based on conditions. Rui supports if, else, and until statements.

If Statements

Use if statements to execute code only when a condition is true:

suppose age = 18

if (age >= 18) {
    write("You are an adult")
}

If-Else Statements

Use else to provide an alternative when the condition is false:

suppose age = 16

if (age >= 18) {
    write("You are an adult")
} else {
    write("You are a minor")
}

If-Else If-Else Statements

Chain multiple conditions using else if:

suppose score = 85

if (score >= 90) {
    write("Grade: A")
} else if (score >= 80) {
    write("Grade: B")
} else if (score >= 70) {
    write("Grade: C")
} else if (score >= 60) {
    write("Grade: D")
} else {
    write("Grade: F")
}

Until Loops

Use until loops to repeat code until a condition becomes true:

suppose count = 0

until (count >= 5) {
    write(count)
    suppose count = count + 1
}

Comparison in Conditions

You can use all comparison operators in conditions:

suppose temperature = 25

if (temperature > 30) {
    write("It's hot outside")
} else if (temperature > 20) {
    write("It's warm outside")
} else if (temperature > 10) {
    write("It's cool outside")
} else {
    write("It's cold outside")
}

Logical Operators in Conditions

Combine conditions using logical operators:

suppose age = 25
suppose hasLicense = true

if (age >= 18 and hasLicense) {
    write("You can drive")
} else {
    write("You cannot drive")
}
suppose weather = "sunny"
suppose temperature = 28

if (weather == "sunny" or temperature > 25) {
    write("Great day for the beach")
}

Nested Conditions

You can nest conditions inside other conditions:

suppose age = 20
suppose hasJob = true
suppose hasCar = false

if (age >= 18) {
    if (hasJob) {
        if (hasCar) {
            write("You can drive to work")
        } else {
            write("You need to find transportation")
        }
    } else {
        write("You should look for a job")
    }
} else {
    write("You're too young to work")
}

Example: Number Guessing Game

Here's a simple number guessing game:

suppose secretNumber = 7
suppose guess = 5

if (guess == secretNumber) {
    write("Congratulations! You guessed correctly!")
} else if (guess < secretNumber) {
    write("Too low! Try a higher number.")
} else {
    write("Too high! Try a lower number.")
}

Example: Countdown Timer

Here's a countdown using an until loop:

suppose countdown = 5

write("Starting countdown...")
until (countdown <= 0) {
    write(countdown)
    suppose countdown = countdown - 1
}
write("Blast off!")

Example: Grade Calculator

Here's a more complex example that calculates grades:

// Student information
suppose studentName = "Alice"
suppose mathScore = 85
suppose scienceScore = 92
suppose englishScore = 78

// Calculate average
suppose average = (mathScore + scienceScore + englishScore) / 3

// Determine grade
if (average >= 90) {
    suppose grade = "A"
} else if (average >= 80) {
    suppose grade = "B"
} else if (average >= 70) {
    suppose grade = "C"
} else if (average >= 60) {
    suppose grade = "D"
} else {
    suppose grade = "F"
}

// Display results
write("Student: " + studentName)
write("Math: " + mathScore)
write("Science: " + scienceScore)
write("English: " + englishScore)
write("Average: " + average)
write("Grade: " + grade)

Next Steps

Now that you understand conditionals, learn about Functions to organize and reuse your code.