One Dimensional Arrays in C Practice Questions with Solutions

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Introduction

A one-dimensional array in C is used to store multiple values of the same data type under one variable name. Instead of creating separate variables for every value, an array lets you store related data in a sequence and access each value using an index. In this chapter, you will practice 1D arrays through beginner-friendly examples covering input, output, sum, average, largest and smallest values, searching, counting, and reversing an array. One Dimensional Arrays in C Practice questions with solutions to help you understand the concepts.

Q1. Create and Print a One-Dimensional Array

Problem Statement

Write a C program to create an integer array containing five numbers and print all its elements.

C Program

#include <stdio.h>

int main()
{
    int numbers[5] = {10, 20, 30, 40, 50};
    int i;

    for (i = 0; i < 5; i++)
    {
        printf("%d ", numbers[i]);
    }

    return 0;
}

Sample Output

10 20 30 40 50

Explanation

This statement creates an array:

int numbers[5];

The number 5 means the array can store five integers.

The array is initialized as:

int numbers[5] = {10, 20, 30, 40, 50};

Array indexing starts from 0.

So the positions are:

Index    Value
  0       10
  1       20
  2       30
  3       40
  4       50

The loop accesses every element using:

numbers[i]

Concepts Covered

  • One-dimensional array
  • Array declaration
  • Array initialization
  • Array indexing
  • for loop

Q2. Take 5 Array Elements from the User

Problem Statement

Write a C program that accepts five integers from the user and then prints them.

C Program

#include <stdio.h>

int main()
{
    int numbers[5];
    int i;

    for (i = 0; i < 5; i++)
    {
        printf("Enter number %d: ", i + 1);
        scanf("%d", &numbers[i]);
    }

    printf("\nArray elements:\n");

    for (i = 0; i < 5; i++)
    {
        printf("%d ", numbers[i]);
    }

    return 0;
}

Sample Output

Enter number 1: 10
Enter number 2: 25
Enter number 3: 15
Enter number 4: 40
Enter number 5: 30

Array elements:
10 25 15 40 30

Explanation

First, we declare:

int numbers[5];

Then the first for loop takes five values.

Notice:

scanf("%d", &numbers[i]);

The value is stored directly at the current array index.

For example:

numbers[0] → first value
numbers[1] → second value
numbers[2] → third value

The second loop prints all the stored values.

Concepts Covered

  • Array input
  • Array indexing
  • scanf()
  • for loop

Q3. Find the Sum of Array Elements

Problem Statement

Write a C program to find the sum of all elements in an integer array.

C Program

#include <stdio.h>

int main()
{
    int numbers[5] = {10, 20, 30, 40, 50};
    int i;
    int sum = 0;

    for (i = 0; i < 5; i++)
    {
        sum = sum + numbers[i];
    }

    printf("Sum = %d", sum);

    return 0;
}

Sample Output

Sum = 150

Explanation

We start with:

int sum = 0;

Then every array element is added:

10 + 20 + 30 + 40 + 50

The loop performs:

sum = sum + numbers[i];

The final result is:

150

Concepts Covered

  • Array traversal
  • Sum of elements
  • for loop
  • Accumulator variable

Q4. Calculate the Average of Array Elements

Problem Statement

Write a C program to calculate the average of five numbers stored in an array.

C Program

#include <stdio.h>

int main()
{
    int numbers[5] = {10, 20, 30, 40, 50};
    int i;
    int sum = 0;
    float average;

    for (i = 0; i < 5; i++)
    {
        sum = sum + numbers[i];
    }

    average = sum / 5.0;

    printf("Average = %.2f", average);

    return 0;
}

Sample Output

Average = 30.00

Explanation

First, we calculate the total:

10 + 20 + 30 + 40 + 50 = 150

Then:

Average = 150 / 5
        = 30

We use:

5.0

instead of:

5

so that the calculation is performed using floating-point arithmetic.

Concepts Covered

  • Array traversal
  • Sum
  • Average
  • float
  • Arithmetic operations

Q5. Find the Largest Element in an Array

Problem Statement

Write a C program to find the largest number in an array.

C Program

#include <stdio.h>

int main()
{
    int numbers[5] = {25, 70, 15, 90, 40};
    int i;
    int largest;

    largest = numbers[0];

    for (i = 1; i < 5; i++)
    {
        if (numbers[i] > largest)
        {
            largest = numbers[i];
        }
    }

    printf("Largest = %d", largest);

    return 0;
}

Sample Output

Largest = 90

Explanation

We initially assume that the first element is the largest:

largest = numbers[0];

So:

largest = 25

Then we compare the remaining elements.

70 > 25  → largest = 70
15 > 70  → no change
90 > 70  → largest = 90
40 > 90  → no change

The final answer is:

90

Concepts Covered

  • Array traversal
  • Largest element
  • if statement
  • Comparison

Q6. Find the Smallest Element in an Array

Problem Statement

Write a C program to find the smallest number in an array.

C Program

#include <stdio.h>

int main()
{
    int numbers[5] = {25, 70, 15, 90, 40};
    int i;
    int smallest;

    smallest = numbers[0];

    for (i = 1; i < 5; i++)
    {
        if (numbers[i] < smallest)
        {
            smallest = numbers[i];
        }
    }

    printf("Smallest = %d", smallest);

    return 0;
}

Sample Output

Smallest = 15

Explanation

We initially store the first element as the smallest:

smallest = numbers[0];

Then every remaining element is compared with it.

The smallest value found is:

15

This is almost the same logic as finding the largest value. The only major difference is the comparison operator:

numbers[i] &lt; smallest

Concepts Covered

  • Array traversal
  • Smallest element
  • Comparison
  • if

Q7. Count Even and Odd Numbers in an Array

Problem Statement

Write a C program to count how many even and odd numbers are present in an array.

C Program

#include <stdio.h>

int main()
{
    int numbers[6] = {10, 15, 20, 25, 30, 35};
    int i;
    int even = 0;
    int odd = 0;

    for (i = 0; i < 6; i++)
    {
        if (numbers[i] % 2 == 0)
        {
            even++;
        }
        else
        {
            odd++;
        }
    }

    printf("Even numbers = %d\n", even);
    printf("Odd numbers = %d", odd);

    return 0;
}

Sample Output

Even numbers = 3
Odd numbers = 3

Explanation

The % operator checks whether a number is divisible by 2.

For example:

10 % 2 = 0 → Even
15 % 2 = 1 → Odd

Whenever an even number is found:

even++;

For an odd number:

odd++;

The array contains:

10, 20, 30 → 3 even numbers
15, 25, 35 → 3 odd numbers

Concepts Covered

  • Array traversal
  • if-else
  • Modulus operator
  • Counting

Q8. Search for an Element in an Array

Problem Statement

Write a C program to search for a particular number in an array and display whether it exists.

C Program

#include <stdio.h>

int main()
{
    int numbers[6] = {10, 25, 30, 45, 50, 60};
    int search;
    int i;
    int found = 0;

    printf("Enter number to search: ");
    scanf("%d", &search);

    for (i = 0; i < 6; i++)
    {
        if (numbers[i] == search)
        {
            found = 1;
            break;
        }
    }

    if (found == 1)
    {
        printf("Number found.");
    }
    else
    {
        printf("Number not found.");
    }

    return 0;
}

Sample Output

Enter number to search: 45
Number found.

Explanation

The user enters a number to search.

Suppose:

search = 45

The loop checks:

10 == 45 → No
25 == 45 → No
30 == 45 → No
45 == 45 → Yes

When the number is found:

found = 1;
break;

The break statement stops the search because there is no need to check the remaining elements.

Concepts Covered

  • Array searching
  • if
  • break
  • Boolean-style flag
  • Array traversal

Q9. Print an Array in Reverse Order

Problem Statement

Write a C program to print the elements of an array in reverse order.

C Program

#include <stdio.h>

int main()
{
    int numbers[5] = {10, 20, 30, 40, 50};
    int i;

    printf("Array in reverse order:\n");

    for (i = 4; i >= 0; i--)
    {
        printf("%d ", numbers[i]);
    }

    return 0;
}

Sample Output

Array in reverse order:
50 40 30 20 10

Explanation

The array contains five elements.

Their indexes are:

0  1  2  3  4

The last element is at index 4.

Therefore, the loop starts from:

i = 4

and moves backward:

4 → 3 → 2 → 1 → 0

The values are printed as:

50 40 30 20 10

Concepts Covered

  • Array indexing
  • Reverse traversal
  • for loop
  • Decrement

Q10. Copy One Array into Another Array

Problem Statement

Write a C program to copy all elements from one array into another array.

C Program

#include <stdio.h>

int main()
{
    int original[5] = {10, 20, 30, 40, 50};
    int copy[5];
    int i;

    for (i = 0; i < 5; i++)
    {
        copy[i] = original[i];
    }

    printf("Copied array:\n");

    for (i = 0; i < 5; i++)
    {
        printf("%d ", copy[i]);
    }

    return 0;
}

Sample Output

Copied array:
10 20 30 40 50

Explanation

We have two arrays:

int original[5] = {10, 20, 30, 40, 50};
int copy[5];

The loop copies each element:

copy[i] = original[i];

The process is:

original[0] → copy[0]
original[1] → copy[1]
original[2] → copy[2]
original[3] → copy[3]
original[4] → copy[4]

The second array now contains the same values.

Concepts Covered

  • Two arrays
  • Array copying
  • Indexing
  • for loop

Key Takeaways

  • A one-dimensional array stores multiple values of the same data type.
  • Array indexing in C starts from 0.
  • For an array of size 5, valid indexes are 0 to 4.
  • Array elements are accessed using the index operator [].
  • A for loop is commonly used to traverse an array.
  • Array elements can be initialized when the array is declared.
  • User input can be stored directly into array elements using scanf().
  • Arrays make it easier to work with collections of related values.
  • Common array operations include sum, average, searching, counting, reversing, and finding minimum or maximum values.
  • Accessing an array outside its valid bounds can lead to undefined behavior.
  • A one-dimensional array is the foundation for understanding two-dimensional and multidimensional arrays.
  • Arrays will become even more useful when combined with functions, pointers, and strings.

FAQs

1. What is a one-dimensional array in C?

A one-dimensional array is a collection of elements of the same data type stored under one variable name.

Example:

int numbers[5];

This array can store five integers.

2. What is the index of the first element in a C array?

The first element has index 0.

For example:

int numbers[3] = {10, 20, 30};

Here:

numbers[0] = 10

3. How do you declare an array in C?

The general syntax is:

data_type array_name[size];

Example:

int marks[5];

4. How do you take input into an array in C?

You can use a loop with scanf():

for (int i = 0; i < 5; i++)
{
    scanf("%d", &numbers[i]);
}

5. How do you print all elements of an array?

Use a loop:

for (int i = 0; i < 5; i++)
{
    printf("%d ", numbers[i]);
}

6. Can an array store different data types in C?

No. A normal C array stores elements of one declared data type.

For example:

int numbers[5];

stores integers.

A float array stores floating-point values:

float prices[5];

7. What is array traversal in C?

Array traversal means visiting or processing each element of an array, usually with a loop.

For example:

for (int i = 0; i < 5; i++)
{
    printf("%d ", numbers[i]);
}

Written by Shubhranshu Shekhar, who has trained 20000+ students in coding.

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