Why arrays are needed in C - Challenge Your Understanding

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of code using arrays for storing multiple values

What is the output of this C program that uses an array to store multiple numbers and prints them?

C

#include <stdio.h>

int main() {
    int numbers[3] = {10, 20, 30};
    for (int i = 0; i < 3; i++) {
        printf("%d ", numbers[i]);
    }
    return 0;
}

A Compilation error

B 10 20 30 40

C 10 20

D 10 20 30

💡 Hint

Look at how many elements are in the array and how many times the loop runs.

The array 'numbers' holds exactly 3 integers: 10, 20, and 30. The loop runs 3 times, printing each element followed by a space.

🧠 Conceptual

intermediate

Why use arrays instead of separate variables?

Why are arrays useful compared to using many separate variables for similar data?

A Arrays let us store many values under one name and access them by index, making code simpler and easier to manage.

B Arrays automatically sort the data for us without extra code.

C Arrays use less memory than separate variables for the same data.

D Arrays prevent any changes to the stored values once set.

💡 Hint

Think about how you would handle a list of scores or names.

Arrays group related data under one name and allow easy access by position, which is simpler than declaring many separate variables.

🔧 Debug

advanced

Identify the error in array usage

What error will this C code produce when compiled or run?

C

#include <stdio.h>

int main() {
    int arr[2] = {1, 2, 3};
    printf("%d", arr[2]);
    return 0;
}

A Prints 3 without error

B Compilation error due to too many initializers

C Prints 0 without error

D Runtime error due to accessing out of bounds

💡 Hint

Check how many elements the array can hold versus how many values are given.

The array is declared to hold 2 integers but initialized with 3 values, which causes a compilation error in C.

❓ Predict Output

advanced

Output when accessing array elements beyond size

What will this C program output?

C

#include <stdio.h>

int main() {
    int nums[3] = {5, 10, 15};
    printf("%d", nums[3]);
    return 0;
}

A Compilation error

B 0

C Undefined behavior, may print garbage or crash

D 15

💡 Hint

Array indices start at 0 and go up to size-1.

Accessing nums[3] is out of bounds since valid indices are 0,1,2. This causes undefined behavior in C.

🚀 Application

expert

How arrays help in storing multiple related data

You want to store the daily temperatures for a week. Which statement best explains why arrays are needed here?

A Arrays allow storing all temperatures in one variable and access each day’s temperature by its position, making data handling easier.

B Arrays automatically calculate the average temperature for the week.

C Arrays prevent any changes to the temperatures once stored.

D Arrays store temperatures as text instead of numbers.

💡 Hint

Think about how you would keep track of multiple values that belong together.

Arrays group multiple related values under one name and allow easy access by index, which is perfect for storing daily temperatures.