3. Conditional Execution

Question 1

body

Answer 1

The sequence of statements within a compound statement.

Question 2

boolean expression

Answer 2

An expression whose value is either True or False.

Question 3

branch

Answer 3

One of the alternative sequences of statements in a conditional statement.

Question 4

chained conditional

Answer 4

A conditional statement with a series of alternative branches.

Question 5

comparison operator

Answer 5

One of the operators that compares its operands: ==, !=, >, =, and <=.

Question 6

conditional statement

Answer 6

A statement that controls the flow of execution depending on some condition.

Question 7

condition

Answer 7

The boolean expression in a conditional statement that determines which branch is executed.

Question 8

compound statement

Answer 8

A statement that consists of a header and a body. The

header ends with a colon (:). The body is indented relative to the header.

Question 9

guardian pattern

Answer 9

Where we construct a logical expression with additional comparisons to take advantage of the short-circuit behavior.

Question 10

logical operator

Answer 10

One of the operators that combines boolean expressions: and, or, and not.

Question 11

nested conditional

Answer 11

A conditional statement that appears in one of the branches of another conditional statement.

Question 12

traceback

Answer 12

A list of the functions that are executing, printed when an exception occurs.

Question 13

short-circuit

Answer 13

When Python is part-way through evaluating a logical expression and stops the evaluation because Python knows the final value for the expression without needing to evaluate the rest of the expression.

Question 14

Rewrite your pay computation to give the employee 1.5 times the hourly rate for hours worked above 40 hours.

Enter hours: 45
Enter Rate: 10
Pay: 475.0

Answer 14

> > > hours = int(input(‘Enter Hours: ‘))

> > > rate = float(input(‘Enter Rate: ‘))

> > > extra_time = hours - 40

> > > if hours > 40:

… pay = (hours - extra_time) * rate + extra_time * rate * 1.5

… else:

… pay = hours * rate

> > > print(‘Pay:’,pay)

Question 15

Rewrite your pay program using try and except so that your program handles non-numeric input gracefully by printing a message and exiting the program. The following shows two executions of the program:

Enter Hours: 20
Enter Rate: nine
Error, please enter numeric input

Enter Hours: forty
Error, please enter numeric input

Answer 15

> > > try:
… hours = int(input(‘Enter Hours: ‘))
… rate = float(input(‘Enter Rate: ‘))
… except:
… print(‘Error, please enter numeric input’)

Question 16

Write a program to prompt for a score between 0.0 and 1.0. If the score is out of range, print an error message. If the score is between 0.0 and 1.0, print a grade using the following table:

Score        Grade
>= 0.9            A
>= 0.8            B
>= 0.7            C
>= 0.6            D
< 0.6              F

~~~

Enter score: 0.95 A ~

Enter score: perfect
Bad score

Enter score: 10.0
Bad score

Enter Score: 0.75
C

Enter score: 0.5
F

Run the program repeatedly as shown above to test the various different values for input.

Answer 16

1) try:
2) score = float(input(‘Enter 3) Score: ‘))
4) except:
5) print(‘Bad Score’)
6) quit()

7) if score > 0.0 and score < 1.0 :
8) if score >= 0.9:
9) print(‘A’)
10) elif score >= 0.8 :
11) print(‘B’)
12) elif score >= 0.7 :
13) print(‘C’)
14) elif score >= 0.6 :
15) print(‘D’)
16) else :
17) print(‘F’)
18) else :
19) print(‘Bad Score’)