String Basics and Memory Representation in DSA C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a string in C?

A string in C is an array of characters ending with a special character called the null terminator '\0' which marks the end of the string.

beginner

Why do C strings end with a null terminator '\0'?

The null terminator '\0' tells functions where the string ends in memory since C does not store string length separately.

beginner

How is a string stored in memory in C?

A string is stored as a sequence of characters in consecutive memory locations, followed by a null terminator '\0'.

intermediate

What happens if a string in C does not have a null terminator?

Without a null terminator, functions that process strings may read beyond the intended end, causing undefined behavior or errors.

beginner

How can you declare and initialize a string in C?

You can declare a string as a char array with initialization like: char str[] = "hello"; which automatically adds the null terminator.

What character marks the end of a string in C?

A ' ' (space)

B '\n' (newline)

C '\0' (null terminator)

D '\t' (tab)

The null terminator '\0' marks the end of a string in C.

How is a string stored in memory in C?

A As a sequence of characters in contiguous memory with a null terminator

B As a number representing the string length

C As a linked list of characters

D As a pointer to a string object

Strings in C are stored as contiguous characters followed by a null terminator.

What happens if a C string is missing the null terminator?

A Functions may read beyond the string causing errors

B The string is treated as empty

C The string length is calculated correctly anyway

D The string is automatically fixed by the compiler

Without a null terminator, string functions may read memory beyond the string causing undefined behavior.

Which of these is a correct way to declare a string in C?

A char str = "hello";

B char str[] = "hello";

C string str = "hello";

D char str[5] = 'hello';

char str[] = "hello"; declares a char array initialized with the string and null terminator.

What is the size in memory of the string "cat" in C?

A Depends on the system

B 3 bytes

C 5 bytes

D 4 bytes

The string "cat" has 3 characters plus 1 null terminator, so 4 bytes total.

Explain how strings are represented and stored in memory in C.

Think about how C knows where the string ends.

Describe the importance of the null terminator in C strings and what can go wrong if it is missing.

Consider how string functions find the string length.