Question

In evaluating the precedence rules used by Python, what statement is accurate? a. Addition and subtraction are evaluated after assignment. b. Exponentiation and assignment operations are left associative. c. Exponentiation has the highest precedence. d. Multiplication is evaluated before unary multiplication.

Answer 1

Answer:

None of the statement a to d can be considered accurate because for:

a) Since assignment is Non associative operator in python, addition and subtraction will be evaluated first before assignment.

b) While Exponent operator has right-to-left associativity in Python, assignment do not have associativity. therefore, both of them are not left associative

c) The operator with highest precedence is Parentheses not Exponentiation

d) The statement is false because it is correct to say "Multiplication have higher precedence than addition and subtraction" and therefore evaluated first, not unary multiplication  

Explanation:

Precedence in Python

Precedence guides the order in which operation are carried out in python.

for example

in 8 - 4 * 2, multiplication is evaluated first because it has higher precedent than subtraction.

Although, the order can be changed using Parentheses ().

example in (10 -4) * 2

values inside Parentheses will be evaluated first.

Associativity of Python operators

Associativity is the order in which an expression that has multiple operator of the same precedence is evaluated .

for example, multiplication ( * ) and floor division ( // ) have same precedence.

Almost all the operators have left-to-right associativity.

Note: operators precedence can be found online in tabular form in the Python documentation

Answer 2

Answer:

c. Exponentiation has the highest precedence.

Explanation:

Operator precedence decides how an expression is evaluated. For example, Multiplication has higher precedence than addition, therefore a+b*c will be evaluated as a + (b*c). (expression in bold is evaluated first, then added to a)

Option a is wrong since assignment ( = ) has the lowest precedence, therefore addition and subtraction will be evaluated first.

Option b is wrong since exponentiation is right associative.

Option d is wrong because multiplication can never be unary.

Precedence of basic python operators is listed below (Order Highest to lowest):

1) Exponentiation (**)

2) Multiplication (*) , Division (/), Modulus (%). (Same rank means equal precedence)

3) Addition (+), Subtraction(-)