All Units Data Types
  1. Using operators
    1. Using mathematical operators
      1. Using integer division
      2. Using modulo to find remainders
      3. Operators on other types
    2. Reading operators
    3. Other operators

Using operators

Operations are performed on data. Operators are syntax indicating what operation to perform.

Using mathematical operators

When programming in Python, the mathematical operators you know and love work just as you might expect.

Operation Operator Example Result
Addition + a = 2 + 2 # a = 4
Subtraction - b = 3 - 4 # b = -1
Multiplication * c = 6 * 3 # c = 18
Division / d = 8 / 2 # d = 4.0
Exponentiation ** exp = 2 ** 2 # exp = 4
  • Notice that the division of two integers results in a float.
  • Computing the exponent uses the ** operator. The ^ operator you may be used to means something different in Python.

You can also add strings. This is called concatenation.

dollars = '$' + str(100) + ',' + str(500)
# dollars = '$100,500'

Using integer division

There is also an integer division operation using the // operator that truncates the result to a whole number by rounding down. Consider these examples:

# integer division always rounds down in the negative direction, not necessarily towards zero
7 // 3      # = 2
-7 // 3     # = -3
# integer division on float values does truncate, but preserves the float type
7.0 // 3.0  # = 2.0
-7.0 // 3.0 # = -3.0
# if even one of the two values in the operation is a float, the result will be a truncated float
7 // 3.0    # = 2.0
-7.0 // 3   # = -3.0

Using modulo to find remainders

Another common operation is to find the remainder of a division. You can accomplish this with the modulo operator %.

# check for remainder
37 % 5  # = 2
# if the remainder is 0, then the dividend is cleanly divisible by the divisor
dividend = 50
divisor = 10
remainder = dividend % divisor
# remainder = 0

Operators on other types

Mathematical operators are commonly used on integers and floats, but they can also be used on other types. For example, strings can be added (concatenated) together with an addition operator:

full_name = 'First' + 'Last'
# full_name = 'First Last'

Make sure you know what type of data you are working with so that you don’t get unexpected results!

Reading operators

An operator applies an operation on the values to the left and right of the symbol. The result of the operation is a new value. Use precedence of operations and parentheses to determine the order in which operations are evaluated.

For example, multiplication has precedence over addition. In this example, the operator * is applied to 4 on its left and 3 on its right.

val = 2 + 4 * 3
# val1 = 14

Using parentheses, the operator * is applied to (2 + 4) on its left and 3 on its right.

val2 = (2 + 4) * 3
# val2 = 18

Here is the order of common operators in Python. The higher up on the list, the greater precedence an operator has.

  1. Parentheses ()
  2. Exponentiation **
  3. Multiplication *
  4. Division /
  5. Integer Division //
  6. Modulo %
  7. Addition +
  8. Subtraction -

Other operators

The mathematical operators are not the only kinds of operators. In most code editors, you will see the keywords and key symbols highlighted in a special color.

Operators can be keywords too, not just key symbols. Consider the in operator which checks if a smaller string is contained in a bigger string and returns a boolean with the result.

message = 'I love doggos'
search = 'dog' in message
# search = True