1. 7 – Variables, Input and Output
CSCI N201
Programming Concepts and Database
7 – Variables, Input and Output
Lingma Acheson
Department of Computer and Information Science, IUPUI

2. Task: Ask the user his or her name, and repeat that name to the user
E.g.
Comp: What is your name?
User: Lingma
Comp: Hi Lingma!

3. Input Requires A question asked by computer An answer to the question
E.g. What is your name?
How old are you?
Where do you live?
How much is two plus two?
An answer to the question
E.g. Lingma 12
Indiana

4. Output Requires Output the answer entered by the user
The answer is stored in computer to be used for output.
“Lingma”
Hi, Lingma!
Lingma

5. Variable A place in memory to hold things Like a container
Different containers for different stuff
Need to plan what and how many variables are needed, and create variables first

6. Variables require: Name – descriptive Init – starting value
Type – kind of data (string, numeric)
Purpose – or description
You can't use a variable if you haven't created the variable
Miracle – “What is your name?”

7. String Data Text Series of alphanumeric characters
Usually enclosed in quotes (“”)
Size depends on length of text

8. Numeric Data Integer (+/-,0, no decimals) Long Integer
Float (includes decimal values)
Double
Size depends on type of number
Miracle – “How old are you?”

9. String Concatenation Technique for combining text “a” + “b” = “ab”
Frequently uses the plus sign
Can be used to combine variables and literals:
Miracle - “Hi,” + userName + “!”

10. Inside the Code Understand the code function main(){ …
} – main structure
// - comments, codes behind this won’t be executed
; - end of a statement
Code is executed line by line

11. Play with Miracle Answer 2 or 3 questions Output a longer sentence
A simple calculator
Adding two numbers and output the result
Ask the user to enter the first number
Ask the user to enter the second number
Change the first variable to integer
Change the second variable to integer
Add the two variables and store in the third variable
Output – “The result is …”