Core Python / Control Statements

1. What is the type and value of x?

   int 10

   Use type(x) and print(x) to verify. or returns the actual value of the first “true” expression. For and if the clause evaluates to True, the last expression evaluated is returned.

2. Why is the order of if and elif clauses important?

   The Python interpreter evaluates the clauses in their listed order. Only the code block associated with the first clause that evaluates to true executes.

3. Explain short-circuit evaluation for and and or clauses.

   Once the Python interpreter can determine the outcome of a Boolean expression, the interpreter no longer needs to continue evaluation.

   For and, if the first expression evaluates to False, the second expression will not be evaluated as the result of the operator will always be False.

   For or, if the first expression evaluates to True, the second expression will not be evaluated as the result of the operator will always be True.

4. How are code blocks identified in Python?

   Indention. This indention must be consistent throughout the source code file. Other programming languages often use curly braces.

5. What is the difference between if/elif statement(s) and a series of if statements?

   With if/elif statements, only the code block associated with the first clause that evaluates to True executes. With a series of if statements, each code block associated with a True clause will evaluate.

6. Why is testing for equality with float numbers problematic? How do we work around such situations?

   Floating-point numbers do not have an exact representation. As such certain calculations may not produce the exact answer expected. Use the math.isclose() instead of the equality operator.