Conditional statements

Conditional statements

Conditional statements are examples of "branching behavior", and they allow your code to perform different tasks depending on certain conditions.

There are a few different forms:

• if
• if-else/elseif
• switch-case

"if"

An if statement allows a block of code to be executed only when certain conditions hold.

        if a < 10
            b = 1
        end
    

• An if statement starts with the "if" keyword.
• A condition follows if.
• It ends with the keyword "end"
• Any list of statements can be included in between.
• Indentations improve readability.

if-else

An if block can include alternate choices.

        if a < 10
            b = 1
        else
            b = 2
        end
    

if-else/elseif

An if block can include multiple choices.

        if a < 10
            b = 1
        elseif a < 20
            b = 2
        else
            b = 3
        end
    

Logical operators

Multiple logical expressions can be combined together using logical operators.

• Logical AND (with short-circuit): &&
• Logical OR (with short-circuit): ||
• Logical NOT ~

        if (a > 3) && (a < 10)
            b = 1
        end
    

Let's try

Read the following code and explain what it does.

        M = magic(5);
        for i = 1:5
            for j = 1:5
                if M(i,j) < 4
                    M(i,j) = 0;
                elseif M(i,j) < 6
                    M(i,j) = 1;
                else
                    M(i,j) = 2;
                end
            end
        end
    

• Count the number of entries in magic(5) that are less than 10 / greater than 20.
• Recreate the following image

More exercises

Can you recreate this image using "for" and "if"?

More exercises

What about this?