19/11/2013 Intro. To Python Session 2 •  Simple data types •  Wri<ng programs •  Selec<on (if statements) Copyright © 2013 Newcastle University 1 Simple data types Strings (str in python) •  A string of 1 or more characters –  'single' or "double" quoted –  Can use one type of quote to include the other in a string •  "Nick's laptop"
•  'Say "goodbye"'
•  Use the + operator to add strings together •  Use \n to include a new line in a string •  Use str() to cast (or convert) another type to a string Copyright © 2013 Newcastle University 2 Numbers •  Integers (whole numbers) –  Use int() to cast (or convert) to an integer –  Using int() on a floa<ng point number gives the whole part part of the number •  Floats –  Floa<ng point number or decimal –  Division / of two numbers results in a float
–  Use // for integer division (% gives the remainder) –  Use float()to cast to a floa<ng point number
•  Long –  For large integers Copyright © 2013 Newcastle University 3 1 19/11/2013 Boolean •  True or False (note capitals) •  Use booleans in logical tests –  To make decisions e.g.: •  A person must be over 21 and have a full licence to hire a car •  What two true/false ques<ons can we ask? •  Like 20 ques<ons (with yes/no, true/false answers) –  Boolean expressions are either true or false •  Use bool() to cast to a boolean –  bool(1) is true and bool(anythingButZero) is true –  bool(0) is false, bool(0.0) is false Copyright © 2013 Newcastle University 4 Comments •  Use comments to document your code •  Comments are not executed –  they are ignored when a program is executed •  Use # for inline or single line comments # this is a comment
print('No comment') # print statement
•  Use triple quotes for mul<-­‐line comments """
This is a comment
And so is this
"""
Copyright © 2013 Newcastle University 5 Two useful library func<ons •  Use time.sleep() to pause a program
import time
time.sleep(10) # pause for 10 seconds
•  Use random.randint() to generate a random number import random
# generate random int between 0 and 100
i = random.randint(0, 100) Copyright © 2013 Newcastle University 6 2