1. Data Types and Conversions, Input from the Keyboard
If you can't write it down in English, you can't code it.                      -- Peter Halpern If you lie to the computer, it will get you.                     -- Peter Farrar

2. What is a Data Type? The type of value stored by a variable
Two general categories:
String: represents text
For now, only use for input/output
More later, if time allows
Numerical
Breaks down into many other types
Types have different internal representations

3. Numerical Data Types int: whole numbers float: decimal point numbers
Computations are exact
float: decimal point numbers
Large range, but fixed precision
Not exact
Example: =

4. Data Types: Differences
Most arithmetic operations behave as you would expect for all data types
Except integer division – result is an integer
Example: result = 5//2
float division behaves as you expect:
Example: result = 5.0/2.0

5. Data Types: Automatic Conversion
int to float:
int op float = float
Examples:
5.0/2
16-(3//2)
16-(3.0/2)
What about: /4?

6. Data Types: Examples of Automatic Conversion
/2 3.0/2 5**31 5.0**31 5.0/ //5 – 2 4.0/5 – 2 4/5 – 2.0

7. Data Types: Explicit Conversion
Python provides functions to do this:
float (<put number here>)
int (<put number here>) #truncates!
If you would rather round to the nearest whole number, use round()
Also takes number as the argument

8. Data Types: Examples of Explicit Conversion
What is the output?
float(3)
int(3.9)
int( )
IDLE: Average of 3 test scores

9. Question: Data Types What is the output of the following code?
result = //2
print result
B. 8
C D. 8.0

10. Keyboard Input Read data from the user during program execution
input() function
How it works:
wait for the user to enter a value
read what has been typed when user enters Enter or Return key

11. Keyboard Input: input()
input(<put prompt string here>)
Prompts the user to enter a number
Assigns entered string to a variable
Example:
greeting = input("Please enter your message: ")

12. Keyboard Input If you want to read an integer, use int() Example:
score = int(input("Please enter exam score: "))
IDLE: Write a program that asks the user for three integer exam scores, and prints the average.