String matching basics in Data Structures Theory - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find if the substring exists in the main string.

Data Structures Theory

if "needle" [1] "haystack":
    print("Found")

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A==

Bnot in

Cin

Dcontains

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of 'in' to check substring presence.

The keyword in checks if one string is inside another.

2fill in blank

medium

Complete the code to get the starting index of the substring in the main string.

Data Structures Theory

index = "haystack".[1]("needle")

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Afind

BindexOf

Clocate

Dsearch

Attempts:

3 left

💡 Hint

Common Mistakes

Using methods that don't exist in Python like 'indexOf'.

The find method returns the first index of the substring or -1 if not found.

3fill in blank

hard

Fix the error in the code to correctly check if the substring is not in the main string.

Data Structures Theory

if "needle" [1] "haystack":
    print("Not found")

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

Ain

Bnot in

C!=

Dis not

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' which compares equality, not substring presence.

The not in keyword checks if a substring is absent from a string.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps words to their lengths only if the length is greater than 3.

Data Structures Theory

{word: [1] for word in words if [2] > 3}

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Alen(word)

Bword

Dword.length

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'word.length' which is not valid in Python.

The comprehension maps each word to its length using len(word), and filters words with length greater than 3.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps uppercase words to their lengths only if the length is less than 5.

Data Structures Theory

{ [1]: [2] for word in words if [3] < 5 }

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Aword.upper()

Blen(word)

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'word' instead of 'word.upper()' for keys.

The comprehension uses word.upper() as keys, maps to len(word), and filters words with length less than 5.