Summary Think Python2 Chapter 5

Chapter 5 Conditionals and recursion




The main topic of this chapter is the if statement, which executes different code depending on the
state of the program. But first two new operators are introduced: floor division and modulus.
5.1 Floor division and modulus
The floor division operator (//) divides 2 integers and round down to an integer. Suppose a movie
is 105 minutes. You want to know how many hours that is. A division returns a floating point:
>>> minutes = 105 1.75
>>> minutes / 60
But you want to know it in an integer. Floor division returns the hours in integer, rounding down:
>>> minutes = 105 1
>>> hours = minutes // 60
>>> hours
To get the remainder you use modulus (%) which divides 2 numbers and returns the remainder:
>>> remainder = minutes % 60 45
>>> remainder
You could also use this to check whether a number is divisible by another: if x % y is 0, then x is
divisible by y. Or you could extract the right most digit(s) from a number: x % 10 yields the right-
most digit of x (in base 10). Similarly x % 100 yields the last two digits.
5.2 Boolean expressions