Find Second Largest Element and Second Largest Element in Array in C

🔷 C Program: Find Second Largest Element in Array

#include <stdio.h>

int main()
{
    int num;
    printf("Enter the number of elements in the array: ");
    scanf("%d", &num);

    if (num < 2)
    {
        printf("Need at least two elements to find second largest>\n");
        return 0;
    }

    int a[num];
    printf("Enter the elements of the array: ");
    for (int i = 0; i < num; i++)
    {
        scanf("%d", &a[i]);
    }

    int first, second;

    if (a[0] > a[1])
    {
        first = a[0];
        second = a[1];
    }
    else if (a[0] < a[1])
    {
        first = a[1];
        second = a[0];
    }
    else
    {
        first = second = a[0];
    }

    for (int i = 2; i < num; i++)
    {
        if (a[i] > first)
        {
            second = first;
            first = a[i];
        }
        else if (a[i] > second && a[i] != first)
        {
            second = a[i];
        }
    }

    printf("The largest element is: %d\n", first);
    if (first == second)
    {
        printf("There is no second largest element (all same or repeated).\n");
    }
    else
    {
        printf("The second largest element is: %d\n", second);
    }

    return 0;
}
  

📘 Explanation:

This program finds the second largest element in a user-provided integer array.

🔹 First, it checks whether the number of elements is at least 2, because a second largest cannot exist with fewer elements.

🔹 Then, it compares the first two elements to initialize the variables first and second.

🔹 As it iterates through the array, it keeps updating first if a larger number is found, and moves the old first into second.

🔹 It also ensures that second is not equal to first by checking a[i] != first to avoid duplicate max values.

🔹 Finally, it prints both the largest and second largest, or a message indicating no distinct second largest exists.

🔍 Sample Output:

Enter the number of elements in the array: 5
Enter the elements of the array: 10 30 20 30 5
The largest element is: 30
The second largest element is: 20

Enter the number of elements in the array: 3
Enter the elements of the array: 40 40 40
The largest element is: 40
There is no second largest element (all same or repeated).
    

🏷️ Keywords:

second largest number in array, largest number C program, array maximum element, array sorting C, C beginner programs, C programming examples