What are algorithms?

Kōrero Mai: What can you remember previously about algorithms?

what are algorithms?

where can you find them?

how can they help in digital technologies?

Computational Thinking: Programs

What is a program?

Program - papatono

A computer program is a list of instructions that tell a computer what to do. Everything a computer does is done by using a computer program. Programs stored in the memory of a computer let the computer do one thing after another, even with breaks in between.

Do you recognise any of the following programs?

Programming languages

Programming Languages - reo papatono

There are many different types of programming languages used to instruct a computer. They are a formal language that is used to convert an algorithm into a computer program. Here are a selection of some of those languages:

Do you recognise any of these logo’s?

Elements of programming languages

There are different elements that make up a programming language, for example:

• Syntax - the form or structure of the language, e.g. some use graphics like Bolt and Scratch and some are text based using words, numbers and punctuation like C#, Python and Javascript.
• Semantics - the meaning of language. Does the programming language typed into a computer make sense?
• Variables - how data, such as numbers, is stored by the computer which can then be used later for mathematical calculations or decision making depending on the program.

Kua reri? - Ready? It's your turn... Turning Algorithms into Programs

Lets now try turning an Algorithm into a program. Turn the image of the Flowchart "Testing a light bulb" into a program. Lets first turn it into Pseudocode to better see the structure.

Pseudocode from a flowchart

Below is an example of one possible solution to the above flowchart

LOOP{
IF LightBulbTurnsOn = true
	OUTPUT "The Light Bulb Works!"
	EXIT
ELSE IF LightBulbIsBlown = true
	OUTPUT "The Light Bulb needs changing"
	EXIT
ELSE IF RoomHasPower = true
	OUTPUT "Call an Electrician"
	EXIT
ELSE IF FuseIsBlown = false
OUTPUT "Call an Electrician"
	EXIT
ELSE
OUTPUT "Flick the fuse back on and try again"
	CHANGE FuseIsBlown => false

Converting pseudocode into C#

Next we will look at what a C# program for this same algorithm looks like. Look for the similarities the program shares with Pseudocode and even flowcharts

using System;

class MainClass {
  public static void Main (string[] args) {
    //Starting values for our Questions / Decisions
    //Use 'true' or 'false'
    bool LightBulbTurnsOn = false;
    bool LightBulbIsBlown = true;
    bool RoomHasPower = false;
    bool FuseIsBlown = false;


    //This is the beginning of the loop
    do{
      if(LightBulbTurnsOn == true){
          Console.WriteLine ("The Light Bulb Works!");

          //We can use 'Break' To exit the loop
          break;
      }
      else if(LightBulbIsBlown == true){
          Console.WriteLine ("The Light Bulb is blown and needs replacing");
          
          //We can use 'Break' To exit the loop
          break;
      }
      else if ...

We can see that given the same inputs (Yes or No responses) we should achieve the same outcome as our flowchart!

Kua reri? - Ready? It's your turn... Try editing the code block below yourself! Try:

• Add in all the missing outputs to the program. Use the flowchart as a guide. C# outputs look like Console.WriteLine("") where the output goes inside the speech marks
• Changing the values at the top from true to false. What happens?
• Can you get all the different outputs to appear?