String as character array in Data Structures Theory - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding String Storage

How is a string typically stored in memory when treated as a character array?

A As a linked list where each node contains a character and a pointer to the next character.

B As a sequence of characters stored in contiguous memory locations, ending with a special null character.

C As a hash table mapping each character to its frequency in the string.

D As a binary tree where each leaf node represents a character.

💡 Hint

Think about how arrays store elements in memory.

Strings as character arrays are stored as a sequence of characters in contiguous memory locations, typically ending with a null character to mark the end.

📋 Factual

intermediate

String Length Calculation

When a string is stored as a character array ending with a null character, how is its length usually determined?

A By storing the length in the first element of the array.

B By counting characters until a space character is found.

C By counting characters until the null character is found.

D By using a separate variable that tracks the length.

💡 Hint

Consider how functions like strlen work in C.

The length is found by counting characters until the null character, which marks the end of the string.

🔍 Analysis

advanced

Modifying Characters in a String Array

Given a string stored as a character array, what happens if you modify a character in the middle of the array?

A The null character is moved to the modified position.

B The entire string is deleted and replaced with the new character.

C The string becomes immutable and cannot be changed.

D The character at that position changes, and the rest of the string remains unchanged.

💡 Hint

Think about how arrays allow element updates.

Since strings as character arrays are mutable, changing one character updates that position without affecting others.

❓ Comparison

advanced

String as Character Array vs Immutable String

Which of the following is a key difference between strings stored as character arrays and immutable string objects?

A Character arrays allow direct modification of characters; immutable strings do not.

B Immutable strings are stored in contiguous memory; character arrays are not.

C Character arrays always use more memory than immutable strings.

D Immutable strings do not have a null terminator; character arrays do not either.

💡 Hint

Consider mutability and how strings behave in different languages.

Character arrays can be changed directly, while immutable strings cannot be altered after creation.

❓ Reasoning

expert

Effect of Missing Null Terminator in Character Array String

What is the likely outcome if a character array intended to represent a string does not have a null terminator?

A Functions that rely on the null terminator will read beyond the array, causing undefined behavior.

B The string will be automatically terminated at the last character of the array.

C The string length will be zero because no terminator is found.

D The program will throw a compile-time error.

💡 Hint

Think about how string functions detect the end of a string.

Without a null terminator, functions keep reading memory past the array, leading to unpredictable results or crashes.