CISC 110 Day 2

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CISC 110Day 2

• Programming Basics

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Outline

• Comments
• Data Types
• Conditional Statements (Branching)
• Loops
• Functions
• Variable Scope

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Comments

• Two Ways to Comment Code
• // This is a comment
• /
• This is a comment spanning multiple
• lines
• /

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Data Types

• Integer (e.g. 5)
• Number (e.g. 5.5)
• String (e.g. Hello!)
• Boolean (true/false)

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Comparison Operations

• Operators
• (is equal to)
• ! (not equal to)
• gt (greater than)
• gt (greater than or equal to)
• lt (less than)
• lt (less than or equal to)

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Boolean Data Type
Example var xBoolean x (1
1) trace(x) Output true
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Conditional Statements

• Statements
• if (something is true)
• execute these lines of code
• else
• else, execute these lines of code

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Conditional Statements
Example var x 10 if(x lt 100)
trace(Howdy!) Output Howdy!
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Conditional Statements
Example var x 100 if(x lt 10)
trace(Howdy!) else trace(Heya) Output
Heya
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Logical Operators

• Operators
• (and) e.g. (true true) true
• (true false) false
• (or) e.g. (true false) true

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Logical Operators
Example var x 1 var y 2 if((x 1)
(y 2)) trace(Howdy!) Output
Howdy!
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While Loop

• Statement
• while (something is true)
• execute these lines of code

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While Loop
Example var x 1 while(x lt 10) x
1 trace(x) Output 10
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For Loop

• Statement
• for(until condition is not true)
• execute these lines of code

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For Loop
Example for(var k 1 k lt 10 k k 1)
trace(!)
Output ! ! ! ! ! ! ! ! !
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For Loop
Example for(var k 1 k lt 10 k)
trace(!)
Output ! ! ! ! ! ! ! ! !
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Functions
Example function displayMessage() trace(I
\m in a function!) displayMessage() Outpu
t Im in a function!
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Function with Argument
Example function displayMessage(messageString)
trace(message) displayMessage(I\m in
a function!) Output Im in a function!
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Function with Arguments
Example function displayMessage(m1String,
m2String) trace(m1m2) displayMessage(
Well, Hello) Output WellHello
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Function with Return Value
Example var sString function
createMessage(xString)String return
Hello x ! s createMessage(CISC
110) trace(s) Output Hello CISC 110!
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Variable Scope
Scope means where variables exist, and can
therefore be accessed, in a program. Local
Variables Variables defined inside a function
only exist within that function. They are
created when the function starts executing and
are destroyed when it finishes. Global Variables
Variables defined outside of a function exist
everywhere after theyre defined, except inside a
function with a duplicate variable name.
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Variable Scope
Example var sString function
createMessage(xString) return Hello x
! s createMessage(CISC
110) trace(x) Output undefined
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Null
null A variable can be assigned to the value
null (e.g. var x null). undefined
Variables should not be assigned to the value
undefined this is the value automatically
assigned to variables that have not been assigned
to any other value.
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