Computational Constructs

Expressions to assign values to variables
Expressions to return values using arithmetic operations (+, -, *, /, ^, mod)
Execution of lines of code in sequence demonstrating input – process- output
Expressions to concatenate strings and arrays using the & operator
Use of selection constructs including simple and complex conditional statements and logical operators.
Iteration and repetition using fixed and conditional loops Pre-defined functions (with parameters)

All code examples are given in Visual basic. You can find more about this topic in chapter 2 of “How to Pass NATIONAL 5 Computing Science”

Expressions to assign values to variables

The end result of an expression represents a value, which is typically of a familiar data type such as Boolean, String, or a numeric type.

Name="Bob the Builder"

Age=16

Expressions to return values using arithmetic operations (+, -, *, /, ^, mod)

The end result of an expression represents a value, which is typically of a familiar data type such as Boolean, String, or a numeric type.

msgbox(length*breadth)

squared=x^2

remainder=11 mod 2

perimeter=2*length+2*breadth

Execution of lines of code in sequence demonstrating input – process- output

Procedural languages follow a predetermined sequence. The program below shows Input, Process and output

name=inputbox("What is your name") 'input
upperName=upper(name) 'process
msgbox("your name in capitals is " & upperName) 'output

Expressions to concatenate strings and arrays using the & operator

Concatenation is the joining together of two or more strings. Array’s can also be concatenated into strings.

fullName=firstName & lastName

Use of selection constructs including simple and complex conditional statements and logical operators.

conditional statements use comparators (Comparison Operators) like >,<,=,<>

Logical operators are used make the comparison more complex AND, OR, NOT

If score>=1000 then msgbox("well done")

if time>12 and hungry=true then msgbox("Lunchtime")

Iteration and repetition using fixed and conditional loops

The terms iteration and repetition are essentially the same thing in programming. They describe the repeated execution of a block of statements. A repetition or iteration structure is a loop statement. It repeats a block of statements once, multiple times or not at all. It all depends on the loop condition and when this condition is tested.

For Counter= 1 to 5 ' fixed loop
   msgbox(counter)
next

Do 'conditional loop
   quit=msgbox("Do you want to quit?",vbYesNo)
loop until quit=vbYes

Pre-defined functions (with parameters)

A pre-defined function is a function that is built into the programming language. Examples include Sin, Cos & Tan

capsName=upper(name)

dice=int(rnd()*6)+1

Exemplification of functions

Hexagon(n)

Repeat 6 Times
Move (n)
Rotate (60)
End Repeat