9_2_2

Activity 1 - READ

All data used needs to have a type. This makes it easier for an application to know what it should and can do with that piece of data.

There are five main types of data:

• Integer (A whole number e.g. 5)
• Real (A decimal number e.g. 5.5)
• Character (A single letter e.g. "A")
• String (A number of characters e.g "A dog went for a walk")
• Boolean (True and False)

Activity 2

Copy and Paste this code into Python and see if it works:

a = input("Enter first number")

b = input ("Enter second number")

print (a+b)

What happens when the code is run? Enter two numbers to see what happens.

If you entered a 4 and then a 5 it would print 45. Why is this?

Activity 3

The default input setting in Python is String. It will think that anything entered via an input is a string unless told otherwise.

Change the code so that it matches the one below:

a = int(input("Enter first number"))

b = int(input ("Enter second number"))

print (a+b)

What has changed?

What happens now when this code is run?

Activity 4

You should now understand how to set a variable input as an integer, but what about the other data types? In Python, the commands to use for each data type are listed below:

• String - str
• Integer - int
• Real - float
• Boolean - bool
• Character - str (with some extra validation - see below)

The simple code below shows how this might all look in Python:

a = int(input("Enter first number"))

b = int(input ("Enter second number"))

c = bool(input("True or False"))

d = float(input("Enter a number"))

e = str(input("Enter a character"))

lengthe=len(e) #checks the length of e <--Validation check

if lengthe>1: #if more than one character is entered

    print ("Data entered is not a character") #data validation check

    e = str(input("Enter a character")) # re-enter data

print (lengthe)

print (a)

print (b)

print (c)

print (d)

print (e)

The line of code where it checks if the length of e is our validation check.

Python doesn't have a data type for character so we must use validation checks to make sure that the right data has been entered.

In Activity 4 you were introduced to validation checks. You can create a validation check for all types of data entered. For character you would use a variation of the example shown. For specific data types you can use something called Try and Except. This is saying... Try to enter this data except when there is a value error.

try:

    a = int(input("Enter first number"))

except ValueError:

    print ("You must enter an integer")

    a = int(input("Enter first number"))

Try this piece of code to see how it works.

Challenge:

Create a questionnaire for a customer to fill in when starting a new Gym. The questionnaire must ask questions that would allow you to practice each data type check. Typical questions might be:

• First initial (char)
• Surname (string)
• Street number (integer)
• Street address (string)
• Weight (real)
• Have you been a member of a gym before? (Boolean)

There are some nice activities on error detection here:

http://csunplugged.org/error-detection/

This could help with the final embed task.