C program to find the second largest element in an array using simple iteration

🔍 Find Second Largest Element in Array (C Program)

#include<stdio.h>

int main()
{
    int num, a[100];
    printf("Enter the size of the array:\n");
    scanf("%d", &num);

    if (num < 2)
    {
        printf("Invalid input! At least two elements are required to find the second largest element.\n");
        return 1;
    }

    printf("Enter %d elements:\n", num);
    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
    {
        first = a[1];
        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];
        }
    }

    if (first == second)
    {
        printf("All elements are equal.\n");
    }
    else
    {
        printf("The second largest element in the array is %d\n", second);
    }

    return 0;
}
  

📘 Explanation:

🔹 The program accepts the size and values of an array.
🔹 It compares the first two elements to initialize `first` and `second`.
🔹 Then, for the rest of the array, it updates these values accordingly:
    – If a new maximum is found, the old maximum becomes second.
    – If it's between first and second and not equal to first, update second.
🔹 If all elements are the same, a message is displayed.

🧪 Sample Output:

Enter the size of the array:
6
Enter 6 elements:
21 45 78 64 90 55
The second largest element in the array is 78
    

🏷️ Keywords:

second largest element in array C, C array comparison, beginner C program, max two values in array, C programming array logic