Why strings are used in Python - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a string variable named greeting with the value 'Hello'.

Python

greeting = [1]

Drag options to blanks, or click blank then click option'

A"Hello"

B123

CHello

DTrue

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to use quotes around the text.

Using a number or boolean instead of text.

Strings are written inside quotes. Here, "Hello" is a string.

2fill in blank

medium

Complete the code to print the string stored in the variable message.

Python

message = "Welcome"
print([1])

Drag options to blanks, or click blank then click option'

Amessage

Bprint

C"message"

DWelcome

Attempts:

3 left

💡 Hint

Common Mistakes

Putting quotes around the variable name, which prints the name itself.

Trying to print the text directly without using the variable.

To print the value of a variable, use its name without quotes inside print().

3fill in blank

hard

Fix the error in the code to concatenate two strings stored in variables first and last.

Python

first = "John"
last = "Doe"
full_name = first [1] last
print(full_name)

Drag options to blanks, or click blank then click option'

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using arithmetic operators like - or * which cause errors with strings.

Forgetting to use an operator between the variables.

The plus sign (+) joins two strings together in Python.

4fill in blank

hard

Fill both blanks to create a dictionary with words as keys and their lengths as values.

Python

words = ["apple", "bat", "car"]
lengths = {word: [1] for word in words if len(word) [2] 3}

Drag options to blanks, or click blank then click option'

Alen(word)

B>

C<

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word itself instead of its length as the dictionary value.

Using < instead of > which changes the filter condition.

len(word) gets the length of each word. The condition filters words longer than 3 letters.

5fill in blank

hard

Fill all three blanks to create a dictionary with uppercase words as keys and their lengths as values for words longer than 2 letters.

Python

words = ["dog", "cat", "a"]
result = { [1]: [2] for w in words if len(w) [3] 2 }

Drag options to blanks, or click blank then click option'

Aw.upper()

Blen(w)

C>

Dw

Attempts:

3 left

💡 Hint

Common Mistakes

Using w instead of w.upper() for keys.

Using < instead of > which changes the filter.

Using w instead of len(w) for values.

w.upper() converts words to uppercase for keys, len(w) gives their length, and > 2 filters words longer than 2 letters.

Practice

1. Why do programmers use strings in Python?

easy

A. To store text like words and sentences

B. To perform mathematical calculations

C. To create loops and conditions

D. To store numbers only

Solution

1. Step 1: Understand what strings represent

   Strings are used to hold text such as words and sentences, not numbers or calculations.

2. Step 2: Identify the correct use of strings

   Since strings hold text, they help programs communicate with people using readable words.

3. Final Answer:

   To store text like words and sentences -> Option A

4. Quick Check:

   Strings = Text storage [OK]

Hint: Strings always hold text inside quotes [OK]

Common Mistakes:

• Thinking strings are for math calculations
• Confusing strings with numbers
• Believing strings control program flow

2. Which of the following is the correct way to write a string in Python?

easy

A. text = 'Hello'

B. text = Hello

C. text = Hello'

D. text = Hello"

Solution

1. Step 1: Check string syntax rules

   Strings must be enclosed in matching quotes, either single ('') or double ("").

2. Step 2: Identify the correct option

   Only text = 'Hello' uses matching single quotes around Hello, making it a valid string.

3. Final Answer:

   text = 'Hello' -> Option A

4. Quick Check:

   Strings need quotes [OK]

Hint: Strings must be inside matching quotes [OK]

Common Mistakes:

• Forgetting quotes around text
• Using mismatched quotes
• Using quotes only on one side

3. What will be the output of this code?

name = 'Alice'
print('Hello, ' + name + '!')

medium

A. Hello, name!

B. Hello, + name + !

C. Hello, Alice!

D. Error: cannot add string and variable

Solution

1. Step 1: Understand string concatenation

   The + operator joins strings together. Here, 'Hello, ' + name + '!' combines the parts into one string.

2. Step 2: Substitute the variable value

   Variable name holds 'Alice', so the output becomes 'Hello, Alice!'.

3. Final Answer:

   Hello, Alice! -> Option C

4. Quick Check:

   Concatenate strings + variable = Hello, Alice! [OK]

Hint: Use + to join strings and variables [OK]

Common Mistakes:

• Printing variable name instead of its value
• Forgetting to use + for joining
• Expecting error from string addition

4. Find the error in this code:

greeting = Hello
print(greeting)

medium

A. Variable name greeting is invalid

B. print() function is misspelled

C. No error, code runs fine

D. Missing quotes around Hello

Solution

1. Step 1: Check string assignment syntax

   Strings must be inside quotes. Here, Hello is not quoted, so Python treats it as a variable.

2. Step 2: Identify the error cause

   Since Hello is not defined as a variable, this causes a NameError.

3. Final Answer:

   Missing quotes around Hello -> Option D

4. Quick Check:

   Strings need quotes to avoid errors [OK]

Hint: Always put quotes around text strings [OK]

Common Mistakes:

• Forgetting quotes around text
• Assuming print is misspelled
• Thinking variable names cause error

5. You want to create a program that asks a user for their name and then greets them with a message. Which of these code snippets correctly uses strings to do this?

hard

A. name = input(Enter your name: )
print('Hello, ' + name + '!')

B. name = input('Enter your name: ')
print('Hello, ' + name + '!')

C. name = input('Enter your name: ')
print('Hello, name!')

D. name = input('Enter your name: ')
print('Hello, ' + 'name' + '!')

Solution

1. Step 1: Check input function usage

   Input prompt must be a string inside quotes. name = input('Enter your name: ') print('Hello, ' + name + '!') uses 'Enter your name: ' correctly.

2. Step 2: Verify greeting message construction

   name = input('Enter your name: ') print('Hello, ' + name + '!') concatenates 'Hello, ' + name + '!' so the user's input is included in the greeting.

3. Final Answer:

   name = input('Enter your name: ') print('Hello, ' + name + '!') -> Option B

4. Quick Check:

   Input prompt and string concat correct [OK]

Hint: Use quotes for prompts and + to join strings [OK]

Common Mistakes:

• Missing quotes in input prompt
• Printing variable name as string
• Concatenating string 'name' instead of variable