Here is a C program to check whether a number is Armstrong number or not. A number is called an Armstrong number if the sum of cubes of every digit of a number is equal to the number itself.
For Example
407 is an Armstrong number
407 = 4*4*4 + 0*0*0 + 7*7*7
121 is not an Armstrong number
121 is not equal to 1*1*1 + 2*2*2 + 1*1*1
- Take a number as input from user and store it in an integer variable(Let's call it inputNumber).
- Find the cubic sum of digits of inputNumber, and store it in sum variable.
- Compare inputNumber and sum.
- If both are equal then input number is Armstrong number otherwise not an Armstrong number..
C program to check a number is Armstrong number or not
This program first takes a number as input from user using scanf function and stores it in variable 'number'. It makes a copy of number in variable 'temp'. Then using a while loop, it calculates the cube of every digit of temp(loop will terminate when temp becomes zero) and stores in a 'sum' variable. If sum is equal to number then it is an Armstrong number otherwise not an Armstrong number.
#include <stdio.h>
int main(){
int number, sum = 0, lastDigit, temp;
printf("Enter a number : ");
scanf("%d", &number);
temp = number;
while(temp != 0){
lastDigit = temp%10;
sum = sum + (lastDigit*lastDigit*lastDigit);
temp = temp/10;
}
if(sum == number){
printf("%d is Armstrong Number \n", number);
} else {
printf("%d is not an Armstrong Number \n", number);
}
return 0;
}
Output
Enter a number : 153 153 is Armstrong Number
Enter a number : 120 120 is not an Armstrong Number
C Program to check whether a number is Armstrong number or not using function
This program uses a user defined function getCubicSumOfDigits that returns the cubic sum of all digits of a number.
#include <stdio.h>
int getCubicSumOfDigits(int number);
int main(){
int number, sum;
printf("Enter a number \n");
scanf("%d", &number);
sum = getCubicSumOfDigits(number);
if(sum == number){
printf("%d is Armstrong Number \n", number);
} else {
printf("%d is not an Armstrong Number \n", number);
}
return 0;
}
int getCubicSumOfDigits(int number){
int lastDigit, sum = 0;
while(number != 0){
lastDigit = number%10;
sum = sum + lastDigit*lastDigit*lastDigit;
number = number/10;
}
return sum;
}
Output
Enter a number 407 407 is Armstrong Number
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