Section Summary

Key Takeaways

• An EXPRESSION is a combination of values (or variables, operators, calls to functions) which evaluates to a value eg ( 1 + 2 )

• Operators are special symbols or keywords which are able to operate on the values and perform (mathematical) operations eg the * operator multiplies 2 values x * y

• Arithmetic operators (+, -, *, /) returns a float if ONE of the values is of the float type

  • % (modulus - divides left operand by right operand and returns the remainder of the operation eg. 5 % 2 = 1

  • ** Exponentiation - left operand raised to the power or right operand eg. 2 * *3 = 8

  • / / Floor/integer division - returns a number resulting from division, but rounded DOWN to the nearest whole number eg 3 // 2.0 = 1.0

• A unary operator is an operator with only 1 operand eg -1 or +3

• A binary operator is an operator with 2 operands eg. 4 + 5, or 12 % 5

• Some operators act before others - the hierarchy of priorities

  • unary + and - have the highest priority

  • then **, then * , / , and % and then the lowest priority: binary + and -

• Sub-expressions in parenthesis are always calculated first eg 15 - 1 * (5 * (1 + 2)) = 0

• The exponentiation operator uses right-sided binding eg 2 ** 2 ** 3 = 256

Exercise 1

What is the output of the following snippet? print((2 ** 4), (2 * 4.), (2 * 4))

16 8.0 8

Exercise 2

What is the output of the following snippet? print((-2 / 4), (2 / 4), (2 // 4), (-2 // 4))

-0.5 0.5 0 -1

Exercise 3

What is the output of the following snippet? print((2 % -4), (2 % 4), (2 ** 3 ** 2))

2 // -4 = -1 --------> Remember floor division -ive so lowest rounding off!! -1 * -4 = 4 2 - (4) = -2 ----- 2 512