Starting Out with Python (4th Edition)
Starting Out with Python (4th Edition)
4th Edition
ISBN: 9780134444321
Author: Tony Gaddis
Publisher: PEARSON
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Textbook Question
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Chapter 9, Problem 1MC

You can use the __________ operator to determine whether a key exists in a dictionary.

a. &

b. in

c. ^

d. ?

Expert Solution & Answer
Check Mark
Program Description Answer

The “in” operator is used to check that key exists in the dictionary.

 Hence, the correct answer is option “B”.

Explanation of Solution

Operator “in”:

  • In Python dictionary, an “in” operator can be used to check if a key exists in the dictionary.
  • The “in” operator returns true if the key exists in the dictionary.
  • Otherwise, the “in” operator returns false.

Syntax:

In Python, the “in” operator can be expressed as follows:

key in dictionary_name

In the above syntax,

  • The “dictionary_name” refers to the dictionary.
  • The “key” represents the key to be searched in the dictionary.

Example program:

# Create a dictionary Student

Student={'Joanne':'CS-1234','Chris':'CS-1235','Jacob':'CS-1236'}

# Check if Joanne exists in the dictionary

if 'Joanne'in Student:

         # Print the value corresponding to key 'Chris'

         print("Value corresponding to key Joanne: " +Student['Joanne'])

Explanation:

In the above Python code, the first line creates a new dictionary “Student” with key-value pair elements “Joanne:CS-1234”, “Chris:1235”, and “Jacob:CS-1236”. The second line checks if the key “Joanne” exists in the dictionary “Student”. The third line prints the value corresponding to “Joanne” if the key “Joanne” exists in the dictionary “Student”.

Explanation for incorrect options:

Operator “&”:

In Python, the “&” operator is used for bitwise “And”.

Hence, option “A” is wrong.

Operator “^”:

In Python, the “^” operator is used for bitwise “Exclusive Or”.

Hence, option “C” is wrong.

Operator “?”:

The “?” is not a built- in operator in Python.

Hence, option “D” is wrong.

Sample Output

Output:

Value corresponding to key Joanne: CS-1234

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Chapter 9 Solutions

Starting Out with Python (4th Edition)

Ch. 9.1 - Prob. 11CPCh. 9.1 - Prob. 12CPCh. 9.1 - What does the values method return?Ch. 9.2 - Prob. 14CPCh. 9.2 - Prob. 15CPCh. 9.2 - Prob. 16CPCh. 9.2 - After the following statement executes, what...Ch. 9.2 - After the following statement executes, what...Ch. 9.2 - After the following statement executes, what...Ch. 9.2 - After the following statement executes, what...Ch. 9.2 - After the following statement executes, what...Ch. 9.2 - Prob. 22CPCh. 9.2 - After the following statement executes, what...Ch. 9.2 - After the following statement executes, what...Ch. 9.2 - Prob. 25CPCh. 9.2 - Prob. 26CPCh. 9.2 - After the following code executes, what elements...Ch. 9.2 - Prob. 28CPCh. 9.2 - After the following code executes, what elements...Ch. 9.2 - After the following code executes, what elements...Ch. 9.2 - After the following code executes, what elements...Ch. 9.2 - Prob. 32CPCh. 9.3 - Prob. 33CPCh. 9.3 - When you open a file for the purpose of saving a...Ch. 9.3 - When you open a file for the purpose of retrieving...Ch. 9.3 - Prob. 36CPCh. 9.3 - Prob. 37CPCh. 9.3 - Prob. 38CPCh. 9 - You can use the __________ operator to determine...Ch. 9 - You use ________ to delete an element from a...Ch. 9 - The ________ function returns the number of...Ch. 9 - You can use_________ to create an empty...Ch. 9 - The _______ method returns a randomly selected...Ch. 9 - The __________ method returns the value associated...Ch. 9 - The __________ dictionary method returns the value...Ch. 9 - The ________ method returns all of a dictionary's...Ch. 9 - The following function returns the number of...Ch. 9 - Prob. 10MCCh. 9 - Prob. 11MCCh. 9 - This set method removes an element, but does not...Ch. 9 - Prob. 13MCCh. 9 - Prob. 14MCCh. 9 - This operator can be used to find the difference...Ch. 9 - Prob. 16MCCh. 9 - Prob. 17MCCh. 9 - The keys in a dictionary must be mutable objects.Ch. 9 - Dictionaries are not sequences.Ch. 9 - Prob. 3TFCh. 9 - Prob. 4TFCh. 9 - The dictionary method popitem does not raise an...Ch. 9 - The following statement creates an empty...Ch. 9 - Prob. 7TFCh. 9 - Prob. 8TFCh. 9 - Prob. 9TFCh. 9 - Prob. 10TFCh. 9 - What will the following code display? dct =...Ch. 9 - What will the following code display? dct =...Ch. 9 - What will the following code display? dct =...Ch. 9 - What will the following code display? stuff =...Ch. 9 - How do you delete an element from a dictionary?Ch. 9 - How do you determine the number of elements that...Ch. 9 - Prob. 7SACh. 9 - What values will the following code display? (Dont...Ch. 9 - After the following statement executes, what...Ch. 9 - After the following statement executes, what...Ch. 9 - After the following statement executes, what...Ch. 9 - After the following statement executes, what...Ch. 9 - After the following statement executes, what...Ch. 9 - What will the following code display? myset =...Ch. 9 - After the following code executes, what elements...Ch. 9 - Prob. 16SACh. 9 - Prob. 17SACh. 9 - Prob. 18SACh. 9 - After the following code executes, what elements...Ch. 9 - Prob. 20SACh. 9 - Write a statement that creates a dictionary...Ch. 9 - Write a statement that creates an empty...Ch. 9 - Assume the variable dct references a dictionary....Ch. 9 - Assume the variable dct references a dictionary....Ch. 9 - Prob. 5AWCh. 9 - Prob. 6AWCh. 9 - Prob. 7AWCh. 9 - Prob. 8AWCh. 9 - Prob. 9AWCh. 9 - Prob. 10AWCh. 9 - Assume the variable dct references a dictionary....Ch. 9 - Write code that retrieves and unpickles the...Ch. 9 - Course information Write a program that creates a...Ch. 9 - Capital Quiz The Capital Quiz Problem Write a...Ch. 9 - File Encryption and Decryption Write a program...Ch. 9 - Unique Words Write a program that opens a...Ch. 9 - Prob. 5PECh. 9 - File Analysis Write a program that reads the...Ch. 9 - World Series Winners In this chapters source code...Ch. 9 - Name and Email Addresses Write a program that...Ch. 9 - Blackjack Simulation Previously in this chapter...Ch. 9 - Word Index Write a program that reads the contents...
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