Module 3Fraser High School

Module 3 – Loops and Booleans

• import statements - random• use the random.randint() function• use while loop• write conditional statements using

comparison operators• use if statements• cast variables using str() and int() functions

Explaining the Guess Number Program

Import Randomimport random

The import command imports external modules that Python has access too. These modules have built in functions that allows us to tap into extra code we can use without having to write it all. There are hundreds of modules that can be used.To access the modules you can useImport module – for example import randomOrFrom module import name

for example from math import sqrt this imports the square root function from the math module

Setting up the variablesThese lines of code assigns the variable guessesTaken the value 0

This prints a welcome screen assigning the variable myName the user input

The final part assigns the variable number with a value the computer generates using the randint (random integer) function from the random module. The computer generates a random integer between 1 and 20.Printing the next line concatenating the text with the variable myName.

The Loop1. This section of the code sets up a

block of code which will loop while the variable guessesTaken is less than 6

2. The computer asks the user for the variable guess (this is the users input)The variable is then cast as an integer

3. The variable guessesTaken is increased by 1

4. The computer compares the users input guess with the computers number – feeding back to the user if the number is too low or too high.

5. If the two number are the same the code breaks from the loop and continues to flow onto the next command

Finishing it offIf you guess the right number that is guess ==number then the computer will return the statement showing how many guesses you took

If you did not guess the right number that is guess != number then the computer will return the statement showing you what the number was

Summary – what instructions did you use

Expressions – unlike statements expressions return something (print 'Nope you got it wrong my number was ' + number)

Assignment statements – simply put we gave value to variables (guessesTaken=0)

Flow Control Statements – if, while and break. They decide which statements are executed. Normal flow is to start from the top and work down, if, while and breakstatements alter this flow.

if guess == number: break

Functions – print() and input() myName=input()

Exercise – Loop practiceSimple While loop example

a = 0 while a < 10: a = a + 1 print a

In Plain English'a' now equals 0 As long as 'a' is less than 10, do the following: Make 'a' one larger than what it already is. print on-screen what 'a' is now worth.

while {condition that the loop continues}: {what to do in the loop} {have it indented, usually four spaces}

{the code here is not looped} {because it isn't indented}

#EXAMPLE #Type this in, see what it does x = 10 while x != 0:

print x x = x - 1

print "wow, we've counted x down, and now it equals", x print "And now the loop has ended."

Try this and see how it works: When you get this try the module 3 exercise – “Table Practice”

http://www.sthurlow.com/python/lesson04/