Joshua July 07, 2021

Before going to the Amstrong number in C, Let's understand how to check a number is Armstrong or not.

If a number is equal to the sum of cubes of its digits, then the number is the Amstrong number. 0, 1, 153, 370 .. are Amstrong numbers.

Let's understand how to check 370 is an Amstrong Number:

           370 = (3*3*3+7*7*7 +0*0*0)

                  = 370

            Hence 370 is an Amstrong Number

To understand this program, You should have knowledge of

• C If else Statement
• C While loop

Program to check Armstrong number in c

    #include<stdio.h>  
    int main()    
    {    
        int num,rem,sum=0,temp;    
        printf("Enter a number: ");    
        scanf("%d",&num);    
        temp=num;    
        while(num>0){    
            rem=num%10;    
            sum=sum+(rem*rem*rem);    
            num=num/10;    
        }    
        if(temp==sum){
            printf("Armstrong Number");  
        }else{
            printf("Not Armstrong Number");  
        }
        return 0;
    }   

Output

          Enter a number: 370
          not armstrong number

0 0

Kenneth July 07, 2021

    #include <stdio.h>

    int main() {
       int temp, rem, sum = 0;
       int armstrong_number = 370; 

       temp = armstrong_number;

       while(temp != 0) {
          rem = temp % 10;
          sum = sum + (rem * rem * rem);
          temp = temp / 10;
       }

       if(sum == armstrong_number) 
          printf("%d is an Armstrong number.", armstrong_number);
       else 
          printf("%d is not an Armstrong number.", armstrong_number);
          
       return 0;
    }

Output

         370 is an Armstrong number.

0 0

Brian July 08, 2021

C program to check Amstrong Number using User Defined Function

    #include <stdio.h>
     
    int checkIsAmstrogNo(int number)
    {
        int temp=number;
        int rem,sum;
         
        sum=0;
        while(temp!=0)
        {
            rem=temp%10;
            sum=sum + (rem*rem*rem);
            temp=temp/10;
        }  
         
        if(sum==number)
            return 1;   //Amstrong Number
        else
            return 0;   //Not an Amstrong Number
    }
     
    int main()
    {
      int num;
      
      printf("Enter an integer number: ");
      scanf("%d", &num);
      
        if(checkIsAmstrogNo(num))
            printf("%d is an Armstrong number.",num);
        else
            printf("%d is not an Armstrong number.",num);
      
      return 0;
    }

Output:

         Enter an integer number: 370
         370 is an Armstrong number.

0 0