C program to check if a number is Pronic or not

C program to check if a number is Pronic or not :

In this tutorial, we will learn how to find a number is Pronic or not. A number is called a Pronic number if it is equal to the product of two consecutive numbers. For example, 7*8 = 56, so 56 is a Pronic number. In this program, we will ask the user to enter a number and then check if it is Pronic or not. Let’s take a look at the program :

C program :

#include <stdio.h>

int main()
{
    //1
    int no;
    int i;
    int flag = 0;

    //2
    printf("Enter a number to check : ");
    scanf("%d", &no);

    //3
    for (i = 0; i <= no; i++)
    { //4
        if (i * (i + 1) > no)
        {
            break;
        }

        //5
        if (i * (i + 1) == no)
        {
            printf("The input number is a Pronic number.\n");
            flag = 1;
            break;
        }
    }

    //6
    if (!flag)
    {
        printf("The input number is not a Pronic number.\n");
    }
}

Explanation :

The commented numbers in the above program denote the step number below :

1. Create one integer no to store the user-input number, integer i to use in the loop and one more integer flag to indicate if it is Pronic or not. flag = 0 means the number is not a Pronic number.
2. Ask the user to enter a number and store it in the variable no.
3. Run one for loop from 0 to the user input no.
4. Check if the product of current number and (current number + 1) is more than the user input no or not. If yes, break from the current loop because it cann’t be a Pronic number.
5. If the product of current number and (current no + 1) is equal to the number no, it is a Pronic number. Print one message , set the value of flag to 1 and break from the loop.
6. If the value of flag is still 0, print that the number is not a Pronic number.

Sample Output :

Enter a number to check : 381
The input number is not a Pronic number.

Enter a number to check : 380
The input number is a Pronic number.

Enter a number to check : 0
The input number is a Pronic number.