Basic Control Flow
Conditional Jumps

The when statement is the simplest of the control flow statements. When a when statement's condition is true, it executes the next line. Otherwise it skips the next line. If you have ever studied or used the languages Java, JavaScript, C, or C++, you should know that a Photon Mint when statement is equivalent to an if statement with no curly braces in any of those 4 languages.
    a = -154
    when a < 0
        print "a is less than 0."        //Will be printed.
    when a > 0
        print "a is greater than 0."     //Won't be printed.
The if statement is the cousin to the when statement. When an if statement begins, it opens a clause. A clause must be closed with an end statement. If the if statement's condition is true, it executes the clause. Otherwise, the clause is ignored. For Java, JavaScript, C, and C++, the Photon Mint if statement is the same as an if statement that does have curly braces.
    a = 200
    b = 300
    if a == 200 and b == 300
        show "a is two hundred and"     //This clause will be executed.
        print " b is three hundred."
    end
    a *= 2
    b *= 2
    if a == 500 and b == 600
        show "a is five hundred and"    //This clause won't be executed.
        print " b is six hundred."
    end
If statements can take an optional else clause, which executes in the event that the if statement is false.
    show "What is your name? "
    name = input
    if name == "Jack"
        print "Hello, Jack!"
    else
        print "Who are you?"
    end
There's also a thing called the if ... else if ... else statement which represents a chain of if statements:
    import time

    today = weekdayNumber()
    if today == 0
        print "Sunday"
    else if today == 1
        print "Monday"
    else if today == 2
        print "Tuesday"
    else if today == 3
        print "Wednesday"
    else if today == 4
        print "Thursday"
    else if today == 5
        print "Friday"
    else
        print "Saturday"
    end
The above if ... else if ... else statement will print the current day of week. Notice that we did 'import time', which imports a library known as time into the current scope. This allows us to call the subprogram weekdayNumber and get the current day of the week as a number. There will be more info about subprograms later. Navigation Previous Lesson: Operators Next Lesson: More Control Flow Table of Contents