Recap: If, elif, else If <True condition>: Do this Elif <True condition>: Otherwise, do this Else:

Compound Statements and Random Numbers

Compound Statements if <condition 1> and <condition 2> You can use compound statements to make sure a block will only run if there is more than one condition to be satisfied if <condition 1> and <condition 2> Then do this if <condition 1> or <condition 2> Will only run if both conditions are true Will only run if at least one condition is true

When you’re finished… How could you make your program start over again and re-prompt the user if the user put in a negative number Add this to your existing code and email me .py file at mcraig@gvsd.org and turn in your grade sheet Read about random numbers and the random module: pages 50-53

Creating while loops While some condition is true, repeat something In coding: you might want to create a quiz show game, while there are questions left, keep playing the game. The while loops lets you do this

What’s a while loop Runs while a certain condition is true Examples: number = int(input("enter a number")) while number !=5 number = int(input(“Guess another number”))

Generating Random Numbers As much as users want consistent, predictable results from programs, sometimes what make the programs exciting is their unpredictability Random numbers can supply an element of surprise Python makes it easy to generate those random numbers Python generates random numbers based on a formula, so they are not truly random. This kind of random generation is called pseudorandom

Introducing the Craps Roller Program Open the Craps Roller Program from the Chapter 3 Folder Craps Roller replicated the dice roll of the fast-paced, casino game of craps. You don’t have to know anything about craps to appreciate the program. Craps Roller just simulates the roll of two, six-sided dice. It displayed the value of each and their total. To determine the dice values, the program uses functions that generates random number. Figure 3.2 shows the program

Importing the random Module The first line of code in the program introduces the import statement The statement allows you to import, or load, modules, in this case, the random module: import random

Modules Modules are files that contain code meant to be used in other programs. These modules usually group together a collection of programming related to one area. The random module contains functions related to generating random numbers and producing random results. When you import a module, it was either installed as part of your Python installation, or was downloaded and installed later on, prior to your running the program that imports it.

Generating Random Numbers You can generate random numbers using: randint() randrange()

randint() Function Produces a random integer Notice the program doesn’t directly call randint() It calls the function: random.randint(1,6) This accesses the function randint() through its module, random

Dot notation You can call a function from an imported module by giving the module name, followed by a period, followed by the function call itself (similar to string methods). This method of action is called dot notation. Using dot notation random.randint() means the function randint() that belongs to the module random. Dot notation can be used to access different elements of imported modules

randint() function Requires two integer argument values and returns a random integer between those two values, which may include either of the argument values. By passing the values 1 and 6 to the function, you are guaranteed to get back either 1,2,3,4,5 or 6

randrange() function produces a random integer Use a single, positive integer argument The function returns a random integer from, and including, 0, up to, but not including, that number Example: random.randrange(6) produces either a 0,1,2,3,4, or 5

Where’s the 6 in the Craps Rollar? randrange(6) is picking a random number from a group of 6 numbers – and the list starts with 0 If you add 1 to the result to get the right value for a die2: die2=random.randrange(6)+1 As a result, die 2 gets either a 1,2,3,4,5, or 6.

Research: What if you want to pick a random string out of a list? What function would you use in python? Do some research and turn in your answer.