String Traversal and Character Access in DSA C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is string traversal in C?

String traversal in C means going through each character of a string one by one, usually using a loop, until the end of the string is reached.

beginner

How do you access the third character of a string named str in C?

You access it using str[2] because indexing starts at 0, so the first character is str[0], second is str[1], and third is str[2].

beginner

What marks the end of a string in C?

A string in C ends with a special character called the null character, written as '\0'. It tells the program where the string stops.

intermediate

Why is it important to check for the null character during string traversal?

Because the null character '\0' marks the end of the string. If you don't check for it, you might read beyond the string and get wrong data or cause errors.

beginner

Show a simple C code snippet to print each character of a string str on a new line.

#include int main() { char str[] = "hello"; int i = 0; while (str[i] != '\0') { printf("%c\n", str[i]); i++; } return 0; }

What does the expression str[i] represent in C when str is a string?

A The character at position i in the string

B The length of the string

C The memory address of the string

D The whole string

str[i] accesses the character at index i in the string str.

Which character indicates the end of a string in C?

A '\n'

B '\0'

C ' ' (space)

D '\t'

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

What will happen if you forget to check for the null character while traversing a string in C?

A The string length will increase

B The program will stop immediately

C The string will become empty

D You might read garbage values beyond the string

Without checking for '\0', traversal can go past the string and read invalid memory.

If char str[] = "abc";, what is the value of str[3]?

A '\0'

B 'a'

C 'c'

D Undefined

The string "abc" is stored as 'a', 'b', 'c', '\0'. So str[3] is the null character.

Which loop is commonly used to traverse a string until its end in C?

A for loop with condition <code>i < length</code>

B do-while loop without condition

C while loop checking <code>str[i] != '\0'</code>

D infinite loop

A while loop checking for str[i] != '\0' is common for string traversal.

Explain how to traverse a string in C and access each character safely.

Think about how to stop at the end of the string.

Describe why the null character is important in C strings and what could happen if it is ignored during traversal.

Consider what tells the program where the string ends.