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Class 1-2: Computer languages

Computer languages are a sequence of instructions composed to perform specific tasks through a computer.  A computer programming language is known as program source coding. A computer machine without a program cannot do ANYTHING. Computer programs can range from two to millions of lines of instructions. Just as there are several languages in the human world, there are also several computer programming languages such as Python, C++, Java, C, Perl, PHP and Ruby.

Our introduction to programming will be through a game called CodeCombat

Class 3: Basics of a computing language

You are to "program" a challenge for the other groups in the classroom. Students are to put a paper X on the floor somewhere within a 50 step radius of the classroom.

We will develop rules for our language in class prior to developing the program. Your group will then write a sequence of lines of code that another group can follow to find your X

Class 5-8:

• Lego assembly and challenge. Using the Mindstorm EV3 program (if not installed, do so using Software Center) develop a set of commands that will lead your robot to WIN

Write-UP: In a presentation document of your choice (Docs/Slides etc...) discuss what went right with your build? What went wrong? How would you fix what went wrong? Refer to research you may have to do on the web in order to apply knowledge about mechanics or programming if it's relevant to your discussion about your successes and/or failures. Include pics of your construction, coding or any other relevant pictures for the challenge(s).

Class 9-15: Introduction to structured language

smallBasic

Microsoft has a freeware package for simple programming called smallBasic. You can use the online IDE here, but is somewhat limited in what you can/can't do

Sequential Programming

Literally, a set of instructions to be run in a pre-programmed sequence. There are several other types of concepts in computer science, but we'll address those shortly. In older versions of programming BASIC sequential lines of code used to be numbered and the computer would actually run according to this number. Number lines are no longer necessary, but still, code runs in order until you tell it to do otherwise - that is from top to bottom and from left to right.

Copy the following into the code window:

'Starting with a text window for the settings

TextWindow.WriteLine("Hello World")

The first line will run, but because it has a quote it is a comment (ie used to document what happens for the programmer, but because it isn't a command it won't appear in the output). The second line runs, and generates a string (words/letters) in the output text window.

TRYTHIS: What about "printing" something else?

Press the large play button (or faster yet, hit F5 if you've installed the program) and what happens? You have written and run your first bit of code! What about a more difficult bit of code. Copy the contents of example_code to the smallbasic code window (will only run if SmallBasic is installed, not on the online IDE). Run it. What do you notice?

Some important terminlogy

• input

  • something a user types into the computer as part of a program

• variable: something that can take on any given value (text or #)

  • a String Variable

    • (usually logical), which holds in memory, some input from a user

    • e.g. name = user's inputted name when prompted

    • a = <text input>

  • Integer Variable

    • mathematical operations can be done on it

    • a = <some number>

    • BEDMAS rules

    • logic a=a+2 works in computer programming, but not in standard math. However a+2 = a doesn't work!

Syntax errors vs. Logic errors

• syntax errors occur when you have typing mistakes. E.g. when you type textWindow.reed instead of textWindow.read in smallBasic. 

• Logic errors occurs when there is a fallacy of reasoning. i.e. In programming, typing if x < 0 and x > 5. Since a value can't be less than 0 and greater than 5, a logical error will occur, but you will not be notified that the code is wrong

Some important terminlogy

• input

  • something a user types into the computer as part of a program

• variable: something that can take on any given value (text or #)

  • a String Variable

    • (usually logical), which holds in memory, some input from a user

    • e.g. name = user's inputted name when prompted

    • a = <text input>

a = TextWindow.Read()

• • Integer or Number Variable

    • mathematical operations can be done on it

    • a = <some number>

a = TextWindow.ReadNumber()

• • • BEDMAS rules

    • logic a=a*2 works in computer programming, but not in standard math. However a*2 = a doesn't work!

How to store a variable:

• string variables

'This stores a variable as a string - and this line is a comment (because of the ' sign)

TextWindow.WriteLine("Please enter your name: ")

wordInput= TextWindow.Read()

TextWindow.Writeline("Pleased to meet you "+ wordInput)

• number variables

'This stores a variable as an integer ( a number)

TextWindow.Writeline("Please enter a number")

numberInput = TextWindow.ReadNumber()

TextWindow.Writeline("Your number is: "+ numberInput)

Conditional Logic

In programming, you can evaluate user inputted integers and strings against stored variables to incredible effect. Typical conditional logic commands include if, then, else. Typical logic would have the programmer checking either inputs or variables against some previous defined value or string to see what outcome should happen. It is important to remember

Usage of conditional logic in english terms can be seen as follows:

If (question) Then

 (do something)

ElseIf (other questions) Then

 (do something else)

Else

 (do something that isn't part of the IF or ELSEIF)

EndIf

So in practical terms:

TextWindow.WriteLine("Please enter a number")

number = TextWindow.ReadNumber() 'inputting a number from the user

if number<10 then 'your variable number is being weighed against the value of 10, the colon is crucial

TextWindow.WriteLine("Your number is <10") 'notice the indent, this means this line of code is UNDER the line above

elseif number > 10 then

TextWindow.WriteLine("Your number is >10")

else

TextWindow.WriteLine("Your number must be 10")

EndIf

Try it yourself with the installed version. Copy/paste this into the client and choose FormatProgram

TextWindow.WriteLine("Please enter a number")

number = TextWindow.ReadNumber() 'inputting a number from the user

if number<10 then 'your variable number is being weighed against the value of 10, the colon is crucial

TextWindow.WriteLine("Your number is <10") 'notice the indent, this means this line of code is UNDER the line above

elseif number > 10 then

TextWindow.WriteLine("Your number is >10")

else

TextWindow.WriteLine("Your number must be 10")

EndIf

BOOLEAN LOGIC

You can ask equivalency in your conditions (as we saw in the example above)

Greater than (>), less than (<) and equal to (=) all apply when making these logic. Likewise the more complex looking "not equal to" (<>)

if number > 10 (number is greater than 10)

if number >=10 (number is greater than or equal to 10)

if number = 10 (if the number is equal to exactly 10)

if number <> 10 (if the number is not equal to 10) 

In other languages (say Python) that the only changes are when making equivalency (==) or not equal to (!=)

You can also string together multiple logic evaluations:

if number<10 and gamePlayLoop =1 then

elseif number=10 and randomNumber <>3 then

Loops

Sometimes we want to repeat lines of code over and over. These are called loops. Mostly beyond the scope of a grade 9 introduction to programming there are 2 types of loops that accomplish this. They are the For and While loops. 

• For loops (when you know how many times the code will run)

  • it has the structure: 

'initializes the loop

For i = 1 To 10

'repeating code goes here

TextWindow.WriteLine(i)

EndFor

• While loops (when you know what will cause the loop to end):

'exits when the answer is equal to 3

answer = 5

while answer <> 3

TextWindow.WriteLine("Please enter a number guess")

answer = TextWindow.ReadNumber()

endwhile

TextWindow.WriteLine("This shows the next line of code after the loop is now executed")

So how do we use structures over and over? Remember the CodeCombat game used While True. We'll do the same:

'notice the WHILE command below means it's going to a loop that happens until you 'break' it. We literally type in the code BREAK to make sure the code/game exits when that condition is reached

'everything has to be indented to be "inside" the while loop

break = "false"

while break = "false"

TextWindow.WriteLine("Enter a number please")

number = TextWindow.ReadNumber()

if number<10 then

  TextWindow.WriteLine("Your number is <10") 'what happens is if the number is less than 10 you get that response

elseif number=10 then

  TextWindow.WriteLine("Your number is equal to 10") 'if it's equal to 10 you get the prompt

else

  break="true" ' if it's larger than 10 the while loop breaks and you're into the statement below.

endif

EndWhile

TextWindow.WriteLine("You found the way out - something greater than 10")

'the print statement above works after the while loop is done because it's indented the same amount as the while statement

'note, you could have instead done break=0 and break =1 for false and true and it would be less typing in the long run