Coding Concepts – Part Two

Variables

Variables hold a specific type of information. Programmers use variables to hold the value of information that may change.  For example, a game program can have a variable to hold the current player’s score.

Microbit variables can be numbers, strings, booleans, sprites and arrays. To use a variable, you assign a type of information it should hold. From that point forward, you can only change the value of that variable to another value of the same type.

  • A number variable could hold numerical data such as the score, the year, age, etc..
  • A string variable holds a string of alphanumeric characters such as a person’s name, a password, address, etc..
  • A Boolean variable has only two values: true or false. For example, you might have certain things that happen only when the variable called Bonus is true.
  • A sprite is a special variable that represents a single dot on the screen and holds two separate values for the row and column the dot is currently in.
  • An array is another special type of variable that holds a list of multiple items.

Iterations

Certain sequence of commands are commonly repeated several times in a program, this is called iteration.  Computer programmers can use a special type of code called a loop around the commands they want to repeat as a form of iteration. A loop repeats code until a certain condition is met.

There are three types of loops in Microsoft Make Code:

  • repeat block – This block repeats the code n number of times.
  • while block – This block runs the code as long as the condition inside of it is true.

for block – This block repeats the code n number of times, but with a variable.

As an example, let us take the last sample program from  Lesson 8: Controlling individual onboard LED and use a for block loop to simplify the program. Assign coordinate y  for the iteration and lit and unlit it five times.  Note that the x coordinate should retain the value 2 since the value of the  horizontal remains the same.

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