Basic Operators

Tutorial

This section explains a bit on how to use basic operators in Python.

Arithmetic Operators

Just as any other programming languages, the addition, subtraction, multiplication, and division operators can be used with numbers.

number = 1 + 2 * 3 / 4.0

Try to predict what the answer will be. Does python follow order of operations?

Another operator available is the modulo (%) operator, which returns the integer remainder of the division. dividend % divisor = remainder.

remainder = 11 % 3

Using two multiplication symbols makes a power relationship.

squared = 7 ** 2 
cubed = 2 ** 3

Using Operators with Strings

Python supports concatenating strings using the addition operator:

helloworld = "hello" + " " + "world"

Python also supports multiplying strings to form a string with a repeating sequence:

lotsofhellos = "hello" * 10

Using Operators with Lists

Lists can be joined with the addition operators:

even_numbers = [2,4,6,8]
odd_numbers = [1,3,5,7]
all_numbers = odd_numbers + even_numbers

Just as in strings, Python supports forming new lists with a repeating sequence using the multiplication operator:

print [1,2,3] * 3

Exercise

The target of this exercise is to create two lists called x_list and y_list, which contain 10 instances of the variables x and y, respectively. You are also required to create a list called "big_list", which contains the variables "x" and "y", 10 times each, by concatenating the two lists you have created.

Tutorial Code

x = object()
y = object()

# change this code
x_list = [x]
y_list = [y]
big_list = []

print "x_list contains %d objects" % len(x_list)
print "y_list contains %d objects" % len(y_list)
print "big_list contains %d objects" % len(big_list)

# testing code
if x_list.count(x) == 10 and y_list.count(y) == 10:
    print "Almost there..."
if big_list.count(x) == 10 and big_list.count(y) == 10:
    print "Great!"

Expected Output

x_list contains 10 objects
y_list contains 10 objects
big_list contains 20 objects
Almost there...
Great!