Character arrays - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of character array initialization

What is the output of this C program?

C

#include <stdio.h>

int main() {
    char arr[] = {'H', 'e', 'l', 'l', 'o'};
    printf("%s", arr);
    return 0;
}

A Random characters or garbage output

B Hello\0

C Compilation error

D Hello

💡 Hint

Remember how strings are represented in C and what %s expects.

The array arr is not null-terminated, so printf with %s reads beyond the array until it finds a null character, causing undefined or garbage output.

❓ Predict Output

intermediate

Length of character array with null terminator

What will be the output of this program?

C

#include <stdio.h>
#include <string.h>

int main() {
    char arr[] = "Hello";
    printf("%zu", strlen(arr));
    return 0;
}

A 6

B Undefined behavior

C Compilation error

D 5

💡 Hint

strlen counts characters until the null terminator, but does not include it.

The string "Hello" is stored with a null terminator, so strlen returns 5, the number of visible characters.

🔧 Debug

advanced

Identify the error in character array assignment

What error will this code produce?

C

#include <stdio.h>

int main() {
    char arr[5];
    arr = "Hello";
    printf("%s", arr);
    return 0;
}

A Output: Hello

B Compilation error: array type is not assignable

C Runtime error: segmentation fault

D Compilation error: missing semicolon

💡 Hint

Think about how arrays and pointers work in C.

Arrays cannot be assigned to after declaration. The line arr = "Hello" is invalid and causes a compilation error.

📝 Syntax

advanced

Correct way to declare and initialize a character array

Which option correctly declares and initializes a character array to hold the string "Code" by explicitly including the null terminator?

A char arr[5] = {'C', 'o', 'd', 'e'};

B char arr[] = "Code";

C char arr[5] = {'C', 'o', 'd', 'e', '\0'};

D char arr[4] = {'C', 'o', 'd', 'e'};

💡 Hint

Remember the null terminator is needed for strings in C.

Option C correctly allocates space for 5 characters including the null terminator and initializes the array properly.

🚀 Application

expert

Number of elements in a character array

Given the code below, what is the value of variable count after execution?

C

#include <stdio.h>

int main() {
    char arr[] = "Programming";
    int count = sizeof(arr) / sizeof(arr[0]);
    printf("%d", count);
    return 0;
}

A 12

B 11

C 10

D Undefined behavior

💡 Hint

Remember that string literals include the null terminator in arrays.

The string "Programming" has 11 characters plus 1 null terminator, so the array size is 12 elements.