String as character array in Data Structures Theory - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to access the first character of the string.

Data Structures Theory

char firstChar = str[1];

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A{0}

B(0)

C[0]

D<0>

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets.

Starting index at 1 instead of 0.

In many programming languages, strings can be treated like arrays of characters. To access the first character, you use square brackets with index 0.

2fill in blank

medium

Complete the code to get the length of the string.

Data Structures Theory

int length = str[1];

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A.index()

B.size()

C.count()

D.length()

Attempts:

3 left

💡 Hint

Common Mistakes

Using .size() which may work in some languages but not all.

Using .count() which counts occurrences of a character.

The .length() method returns the number of characters in a string.

3fill in blank

hard

Fix the error in accessing the last character of the string.

Data Structures Theory

char lastChar = str[1];

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A[str.length() + 1]

B[str.length() - 1]

C[str.length()]

D[str.length() * 1]

Attempts:

3 left

💡 Hint

Common Mistakes

Using str.length() as index which is out of bounds.

Adding 1 to length causing an error.

Since string indices start at 0, the last character is at index length - 1.

4fill in blank

hard

Fill both blanks to create a substring from index 2 to 5.

Data Structures Theory

String sub = str[1]([2], 4);

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A.substring

B2

C3

D.substr

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong method name.

Starting at the wrong index.

The .substr(start, length) method extracts a part of the string starting at index start with the given length.

5fill in blank

hard

Fill all three blanks to create a dictionary of characters and their counts from the string.

Data Structures Theory

charCount = [1](c: str[[2]] for [3] in range(len(str)))

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Adict

Bi

Dlist

Attempts:

3 left

💡 Hint

Common Mistakes

Using a list instead of a dictionary.

Using a variable name other than the loop index.

This code creates a dictionary where each character from the string is a key. It uses a loop variable i to access each character by index.