Decisions In today’s lesson we will look at: what we mean by a decision the sorts of decisions a program might need to take programming a decision in Python

Decisions We need to make decisions all the time – what time to get up, what to eat, how to start your essay, etc. In programming, the word decision has the same sort of meaning. Can you think of a program that does exactly the same thing every time? Most programs make some sort of decision

Decisions What sort of things will your program make decisions based on? Your program might need to react to: what the user does what happens in the program the values of particular variables an external factor, such as date or time

Programming Decisions Most programming languages – and even spreadsheets – use an if command to make a decision In Python, the format is: if [test condition]: [command] For example... if x > 10: print(“X is bigger than 10”)

Multiple Commands There is an expanded form of IF that allows you to do more than one thing: if a > b: a = a + b b = a – b a = a – b print(“Always done”)

Alternatives You can also use the ELSE command to give an alternative: if a > 10: print(“a is bigger than 10”) else: print(“a isn’t bigger than 10”) print(“Always done”)