CS105: Introduction to Python

In Python, addition and subtraction operators perform just as they do in mathematics. In fact, you can use the Python programming language as a calculator.

Let's look at some examples, starting with integers:

print(1 + 5)

Output:

6

Instead of passing integers directly into the print statement, we can initialize variables to stand for integer values:

a = 88
b = 103
print(a + b)

Output:

191

Because integers can be both positive and negative numbers (and 0 too), we can add a negative number with a positive number:

c= -36
d = 25
print(c + d)

Output:

-11

Addition will behave similarly with floats:

e = 5.5
f = 2.5
print(e + f)

Output:

8.0

Because we added two floats together, Python returned a float value with a decimal place.

The syntax for subtraction is the same as for addition, except you'll change your operator from the plus sign (+) to the minus sign (-):

g = 75.67
h = 32
print(g - h)

Output:

43.67

Here, we subtracted an integer from a float. Python will return a float if at least one of the numbers involved in an equation is a float.