Transcript Math Operators in Python

Operators in Python
Arithmetic operators
• Some operators in Python will look familiar (+, -, *, /)
• Others are new to you (%, //, **)
• All of these do work with numbers and produce numbers
For any operator you need to know
• These are questions you should ask every time you see a new
operator – not just arithmetical but any operator!
• How many arguments does it have and what do they mean
• What data type are the arguments? (int, float, string, etc.)
• The semantics of the operator, which is what does it do? What does
it mean?
• What data type does the operator return? NOT always the same as
the type of the arguments
• What is its precedence or priority with other operators?
Example: addition +
• It has two arguments (we are talking about the addition operator
here, not the unary plus sign)
• The arguments can be ints or floats
• It produces the sum of the values of the two arguments
• It produces an integer if the arguments are both integers, otherwise it
produces a floating point number
• It is relatively low precedence, comes after * and /
Other familiar operators
• Multiplication * works on ints and floats, produces an int if 2 int
arguments, float otherwise
• Subtraction works similarly to multiplication
• Division / works on ints and floats, but always returns a float
• Precedence is as in algebra, multiplication and division higher than
addition and subtraction
• If there are two operators in an expression of the same level of
precedence, they are executed left to right in the expression
• a + b + c is done as (a + b) + c
New Operators // and %
• // is similar to division but always gives the whole number part of the
quotient (result of dividing)
• If give two ints, will give an int, otherwise a float
• 5 // 4 = 1, 5 // 4.0 = 1.0 (not 1.25)
• % is the modulus operator, gives the remainder of a division
operation
• If give two ints, yields an int, otherwise a float
• 13 % 4 = 1 (the remainder when 13 is divided by 4), 8 % 4 = 0
• These two operators have the same precedence as multiplication and
division
New Operator **
• ** means exponentiation
• Has two arguments a ** b
• a is the base, b is the power to raise a to
• 5 **3 = 5 * 5 * 5, 7 ** 2 = 7 * 7 = 49
• The precedence is higher than the other arithmetic operators
• The base or power can be integer or float
• As usual, if two int arguments, gives int result, otherwise float
• Is right associative (different from all of the other operators)
• 4 ** 3 ** 2 = 4 ** (3 ** 2) = 4 ** 9 = 262144