C Program to Find the Greatest of Three Numbers

The program determines greatest among three numbers based on the conditional statements. It simply uses greater than (>) and smaller than (<)  comparison operators to find greatest number. There are two ways to achieve this functionality. First one is by using if-else statement and other is using ternary operator.

Approach To Find Greatest of Three :

It is required to find the largest numbers among three numbers. The solution is quite easy and simple :

• Get three numbers from the user as input
• Check the first number whether it is greater than the second one or not
• Similarly, check again the same number with the third one
• If a number is greater than the rest,
• The number would be qualified as greatest among all

C program to find the greatest of three numbers using If-else statement

In case of if-else statement, we have used nested if-else condition to find greatest of three numbers in the below C program.

Program:

#include <stdio.h>

int main ()
{
  int num, num1, num2;
  printf ("Please enter first number : ");
  scanf ("%d", &num);

  printf ("Please enter second number : ");
  scanf ("%d", &num1);

  printf ("Please enter third number : ");
  scanf ("%d", &num2);

  printf ("\n******* Finding Greatest ******* \n");
  if (num > num1)
    {
      if (num > num2)
  {
    printf ("\n%d is Greatest \n", num);
  }
      else
  {
    printf ("\n%d is Greatest \n", num2);
  }
    }
  else if (num1 > num2)
    {
      printf ("\n%d is Greatest \n", num1);
    }
  else
    {
      printf ("\n%d is Greatest \n", num2);
    }
  return 0;
}

Output:

Please enter first number : 4                                                                                            Please enter second number : 76                                                                                          Please enter third number : 43                                                                                                                                                                                                                    ******* Finding Greatest *******                                                                                                                                                                                                                 
 76 is Greatest

Explanation:

1) Taking three variables named num,num1,num2 assigned with 4,20,5 values respectively
2) if ‘num’ is greater than num1 and num2 then it would be printed as the largest number
3) if ‘num’ is smaller than num1, ‘else-if’ block would be executed that check if num1 is greater than ‘num’ or not

4) if it returns false, in that case, ”else’ block would be executed and “num2” become the greatest

C program to find the greatest of three numbers using ternary operator

program :

#include <stdio.h>

int main ()
{
  int num, num1, num2;
  printf ("Please enter first number : ");
  scanf ("%d", &num);

  printf ("Please enter second number : ");
  scanf ("%d", &num1);

  printf ("Please enter third number : ");
  scanf ("%d", &num2);

  printf ("\n******* Finding Greatest ******* \n");
  (num > num1) ? ( (num > num2)? printf ("\n%d is Greatest \n", num): printf ("\n%d is Greatest \n", num2) ) :   ( (num1 > num2) ? printf ("\n%d is Greatest \n", num1): printf ("\n%d is Greatest \n", num2));

  return 0;
}

Output :

Please enter first number : 4                                                                                            Please enter second number : 87                                                                                          Please enter third number : 109                                                                                                                                                                                                                   ******* Finding Greatest *******                                                                                                                                                                                                      
            109 is Greatest

In the above example, we used ternary operator with same approach to find greatest number.