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Starting Out with Python (4th Edition)
4th Edition
ISBN: 9780134444321
Author: Tony Gaddis
Publisher: PEARSON
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Expert Solution & Answer
Chapter 4.5, Problem 18CP
Explanation of Solution
Sentinel:
Sentinel is the special value which is used to stop the sequence of series when there is no indication of explicit size.
- • It is also called as “flag value” or “dummy value” created in the
algorithm to terminate theprogram . - • The sentinel value must be a distinct value from the other data values, so that it is guaranteed to end the data.
- ○ For example: “null character” is used to end the null terminated string and a “negative integer” is used to indicate the end of sequence for non-negative integers.
- • Whenever the program reads the sentinel value it stops the execution of loop, because it knows that it reaches the end of sequence.
Example program:
The following program code uses the sentinel value:
#Initialize the variables
total = 0
counter = 0
# Get the marks
Marks = int( input("Enter marks, -1 to end: "))
'''Check loop if marks not equal to -1 sentinel value to terminate the loop'''
while Marks != -1:
# Calculate the total
total = total + Marks
# Increment the counter by 1
counter = counter + 1
...
Expert Solution & Answer
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Chapter 4 Solutions
Starting Out with Python (4th Edition)
Ch. 4.1 - What is a repetition structure?Ch. 4.1 - What is a condition-controlled loop?Ch. 4.1 - What is a count-controlled loop?Ch. 4.2 - What is a loop iteration?Ch. 4.2 - Does the while loop test its condition before or...Ch. 4.2 - How many times will 'Hello world' be printed in...Ch. 4.2 - What is an infinite loop?Ch. 4.3 - Rewrite the following code so it calls the range...Ch. 4.3 - What will the following code display? For number...Ch. 4.3 - What will the following code display? for number...
Ch. 4.3 - What will the following code display? for number...Ch. 4.3 - What will the following code display? for number...Ch. 4.4 - Prob. 13CPCh. 4.4 - Should an accumulator be initialized to any...Ch. 4.4 - What will the following code display? total - 0...Ch. 4.4 - What will the following code display? number 1 =...Ch. 4.4 - Rewrite the following statements using augmented...Ch. 4.5 - Prob. 18CPCh. 4.5 - Why should you take care to choose a distinctive...Ch. 4.6 - What does the phrase garbage in, garbage out mean?Ch. 4.6 - Give a general description of the input validation...Ch. 4.6 - Describe the steps that are generally taken when...Ch. 4.6 - Prob. 23CPCh. 4.6 - If the input that is read by the priming read is...Ch. 4 - A_________-controlled loop uses a true/false...Ch. 4 - A _____-controlled loop repeats a specific number...Ch. 4 - Each repetition of a loop is known as a(n) a cycle...Ch. 4 - The while loop is a _______ type of loop. a....Ch. 4 - A(n) ______ loop has no way of ending and repeats...Ch. 4 - The -= operator is an example of a(n) _________...Ch. 4 - Prob. 7MCCh. 4 - A(n) ____________ is a special value that signals...Ch. 4 - Prob. 9MCCh. 4 - The integrity of a programs output is only as good...Ch. 4 - The input operation that appears just before a...Ch. 4 - Validation loops are also known as _________. a....Ch. 4 - A condition-controlled loop always repeats a...Ch. 4 - The while loop is a pretest loop.Ch. 4 - The following statement subtracts 1 from x: x = x ...Ch. 4 - It is not necessary to initialize accumulator...Ch. 4 - In a nested loop, the inner loop goes through all...Ch. 4 - To calculate the total number of iterations of a...Ch. 4 - The process of input validation works as follows:...Ch. 4 - What is a condition-controlled loop?Ch. 4 - What is a count-controlled loop?Ch. 4 - What is an infinite loop? Write the code for an...Ch. 4 - Why is it critical that accumulator variables are...Ch. 4 - What is the advantage of using a sentinel?Ch. 4 - Prob. 6SACh. 4 - What does the phrase garbage in, garbage out mean?Ch. 4 - Give a general description of the input validation...Ch. 4 - Write a while loop that lets the user enter a...Ch. 4 - Write a while loop that asks the user to enter two...Ch. 4 - Write a for loop that displays the following set...Ch. 4 - Write a loop that asks the user to enter a number....Ch. 4 - Write a loop that calculates the total of the...Ch. 4 - Rewrite the following statements using augmented...Ch. 4 - Write a set of nested loops that display 10 rows...Ch. 4 - Write code that prompts the user to enter a...Ch. 4 - Write code that prompts the user to enter a number...Ch. 4 - Bug Collector The Bug Collector Problem A bug...Ch. 4 - Calories Burned Running on a particular treadmill...Ch. 4 - Budget Analysis Write a program that asks the user...Ch. 4 - Distance Traveled The distance a vehicle travels...Ch. 4 - Average Rainfall Write a program that uses nested...Ch. 4 - Celsius to Fahrenheit Table Write a program that...Ch. 4 - Pennies for Pay Write a program that calculates...Ch. 4 - Sum of Numbers Write a program with a loop that...Ch. 4 - Ocean Levels Assuming the ocean's level is...Ch. 4 - Tuition Increase At one college, the tuition for a...Ch. 4 - Weight Loss If a moderately active person cuts...Ch. 4 - Calculating the Factorial of a Number In...Ch. 4 - Population Write a program that predicts the...Ch. 4 - Prob. 14PECh. 4 - Prob. 15PECh. 4 - Turtle Graphics: Repeating Squares In this...Ch. 4 - Turtle Graphics: Star Pattern Use a loop with the...Ch. 4 - Turtle Graphics: Hypnotic Pattern Use a loop with...Ch. 4 - Turtle Graphics: STOP Sign In this chapter, you...
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