Basic Operators

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This section explains 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
print(number)

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
print(remainder)

Using two multiplication symbols makes a power relationship.

squared = 7 ** 2
cubed = 2 ** 3
print(squared)
print(cubed)

Using Operators with Strings

Python supports concatenating strings using the addition operator:

helloworld = "hello" + " " + "world"
print(helloworld)

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

lotsofhellos = "hello" * 10
print(lotsofhellos)

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
print(all_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.

x = object() y = object() # TODO: 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!") x = object() y = object() # TODO: change this code x_list = [x] * 10 y_list = [y] * 10 big_list = x_list + y_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!") Ex().check_object('x_list').has_equal_value(expr_code = 'len(x_list)') Ex().check_object('y_list').has_equal_value(expr_code = 'len(y_list)') Ex().check_object('big_list').has_equal_value(expr_code = 'len(big_list)') success_msg('Good work!')

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