Armstrong Number
If the given number is equal to the sum of the power of n for each digit present in that integer then, that number can be Armstrong Number. For example 153 is Armstrong Number.
Number of individual digits in 153 = 3
153 = 1³ + 5³ + 3³
= 1 + 125 + 27 = 153
Below steps will show you the common approach to check for the Armstrong Number
Steps:
- Enter any number
- Divide the given number into individual digits (For Example, Divide 153 into 1, 5 and 3)
- Calculate the power of n for each individual and add those numbers
- Compare original value with Sum value.
- If they exactly matched then it is Armstrong number else it is not Armstrong
In this article we will show you, How to Write C Program For Armstrong Number Using While Loop, For Loop, Functions and Recursion. We will also show you, Armstrong Numbers between 1 to n.
C Program for Armstrong Number Using While Loop
This C program allows the user to enter any positive integer and then, this program will check whether a number is Armstrong Number or Not using the While Loop
/* C Program For Armstrong Number */
#include
#include
int main()
{
int Number, Temp, Reminder, Times =0, Sum = 0;
printf("\nPlease Enter number to Check for Armstrong \n");
scanf("%d", &Number);
//Helps to prevent altering the original value
Temp = Number;
while (Temp != 0)
{
Times = Times + 1;
Temp = Temp / 10;
}
Temp = Number;
while( Temp > 0)
{
Reminder = Temp %10;
Sum = Sum + pow(Reminder, Times);
Temp = Temp /10;
}
printf("\n Sum of entered number is = %d\n", Sum);
if ( Number == Sum )
printf("\n %d is Armstrong Number.\n", Number);
else
printf("\n %d is not a Armstrong Number.\n", Number);
return 0;
}
OUTPUT
ANALYSIS
This program allows the user to enter any positive integer and then, that number is assigned to variable Number.
Next, We assign the original value to the Temp variable. This will help us to preserve our original value and then do all the manipulation on Temp variable.
Below While loop will make sure that, the given number is greater than 0. Statements inside the while loop will split the numbers and counts number of individual digits inside the given number. If you don’t understand the logic, Please refer C Program to Count Number Of Digits in a Number article.
while (Temp != 0)
{
Times = Times + 1;
Temp = Temp / 10;
}
User Entered value: Number = 1634 and Sum = 0
Temp = Number
Temp = 1634
First Iteration
Reminder = Temp %10
Reminder = 1634 % 10 = 4
Sum = Sum + pow (Reminder, Times)
For this example, Times = 3 because number of digits in 1634 = 4. So pow() function will multiply the Reminder 4 times as shown below
Sum = Sum + (Reminder * Reminder * Reminder * Reminder)
Sum = 0 + (4 * 4 * 4 * 4)
Sum = 0 + 256
Sum = 256
Temp = Temp /10
Temp = 1634 /10
Temp = 163
NOTE: If the number of digits count is 5 then Reminder will be multiplied by 5 times.
Second Iteration
From the first Iteration the values of both Temp and Sum has been changed as: Temp = 163 and Sum = 256
Reminder = Temp %10
Reminder = 163 % 10 = 3
Sum = Sum + (Reminder * Reminder * Reminder * Reminder)
Sum = 0 + (3 * 3 * 3 * 3)
Sum = 256 + 81
Sum = 337
Temp = Temp /10
Temp = 163 /10
Temp = 16
Third Iteration
From the Third Iteration the values of both Temp and Sum has been changed as: Temp = 16 and Sum = 337
Reminder = Temp %10
Reminder = 16 % 10 = 6
Sum = Sum + (Reminder * Reminder * Reminder * Reminder)
Sum = 0 + (6 * 6 * 6 *6)
Sum = 337 + 1296
Sum = 1633
Temp = Temp /10
Temp = 16 /10
Temp = 1
Fourth Iteration
From the Fourth Iteration the values of both Temp and Sum has been changed as: Temp = 1 and Sum = 1633
Reminder = Temp %10
Reminder = 1 % 10 = 0
Sum = Sum + (Reminder * Reminder * Reminder * Reminder)
Sum = 1633 + (1 * 1 * 1 * 1)
Sum = 1633 + 1
Sum = 1634
Temp = Temp /10
Temp = 1/10
Temp = 0
Here Number = 0 so, the while loop condition will fail
if ( Number == Sum ) – Condition will check whether the user enter number is exactly equal to Sum number or not. If this condition is True, then it is Armstrong else the given number is not Armstrong number
if ( Number == Sum ) => if(1634 == 1634) –TRUE. So, Number is an Armstrong Number
NOTE: If you are finding the Armstrong number below 1000 then you can simply remove the while loop to count the number of digits in a number and then replace the below code
Sum = Sum + pow(Reminder, Times); With Sum = Sum + (Reminder * Reminder * Reminder)
C Program for Armstrong Number Using For Loop
This program allows the user to enter any positive integer and then, this program will check whether a number is Armstrong Number or Not using For Loop
/* C Program For Armstrong Number using For loop */
#include
#include
int main()
{
int Number, Temp, Reminder, Times =0, Sum = 0;
printf("\nPlease Enter any number to Check for Armstrong \n");
scanf("%d", &Number);
Temp = Number;
while (Temp != 0)
{
Times = Times + 1;
Temp = Temp / 10;
}
for(Temp = Number; Temp > 0; Temp = Temp /10 )
{
Reminder = Temp % 10;
Sum = Sum + pow(Reminder, Times);
}
printf("\nSum of entered number is = %d\n", Sum);
if ( Number == Sum )
printf("\n%d is Armstrong Number.\n", Number);
else
printf("%d is not the Armstrong Number.\n", Number);
return 0;
}
OUTPUT
We just replaced the While loop in the above example with the For loop. If you don’t understand the for loop then please refer For Loop article here: For Loop in C Programming
C Program for Armstrong Number Using Functions
This C program allows the user to enter any positive integer and then, this program will check whether a number is Armstrong Number or Not using Functions
/* C Program For Armstrong Number using Functions*/
#include <stdio.h>
#include <math.h>
int Check_Armstrong (int);
int main()
{
int Number, Sum = 0;
printf("\nPlease Enter any number to Check for Armstrong \n");
scanf("%d", &Number);
Sum = Check_Armstrong (Number);
printf("Sum of entered number is = %d\n", Sum);
if ( Number == Sum )
printf("\n%d is Armstrong Number.\n", Number);
else
printf("%d is not Armstrong Number.\n", Number);
return 0;
}
int Check_Armstrong (int Number)
{
int Temp, Reminder, Times =0, Sum = 0;
Temp = Number;
while (Temp != 0)
{
Times = Times + 1;
Temp = Temp / 10;
}
for(Temp = Number; Temp > 0; Temp = Temp /10 )
{
Reminder = Temp %10;
Sum = Sum + pow(Reminder, Times);
}
return Sum;
}
OUTPUT
ANALYSIS
When the compiler reaches to
Sum = Check_Armstrong (Number); line in main() program then the compiler will immediately jump to below function:
int Check_Armstrong (int Number)
We already explained LOGIC above example.
NOTE: If we create a function with Void then there is no need to return any value but, if we declared a function with any data type (int, float etc) then we have return something out from the function.
C Program for Armstrong Number Using Recursion
This C program allows the user to enter any positive integer and then, this program will check whether a number is Armstrong Number or Not using Recursion concept.
/* C Program For Armstrong Number using Recursion */
#include <stdio.h>
#include <math.h>
int Check_Armstrong (int, int);
int main()
{
int Number, Sum = 0, Times =0,Temp;
printf("\nPlease Enter number to Check for Armstrong \n");
scanf("%d", &Number);
Temp = Number;
while (Temp != 0)
{
Times = Times + 1;
Temp = Temp / 10;
}
Sum = Check_Armstrong (Number, Times);
printf("Sum of entered number is = %d\n", Sum);
if ( Number == Sum )
printf("\n%d is Armstrong Number.\n", Number);
else
printf("%d is not the Armstrong Number.\n", Number);
return 0;
}
int Check_Armstrong (int Number, int Times)
{
static int Reminder, Sum = 0;
if (Number > 0)
{
Reminder = Number %10;
Sum = Sum + pow(Reminder, Times);
Check_Armstrong (Number /10, Times);
return Sum;
}
else
return 0;
}
OUTPUT
ANALYSIS
In this function,
Armstrong_Check (Number /10);
Statement will help to call the function Recursively with updated value. If you miss this statement then, after completing the first line it will terminate. For example,
Number = 153
Then the output will be 27
Lets see the If condition
if (Number > 0) will check whether the number is greater than 0 or not. For Recursive functions it is very important to place a condition before using the function recursively otherwise, we will end up in infinite execution (Same like infinite Loop).
Please be careful 🙂
C Program to Find Armstrong Numbers between the 1 to n
This program allows the user to enter minimum and maximum values. This program will find the Armstrong Numbers between the Minimum and Maximum values.
/* C Program for Armstrong Number between 1 to n */
#include<stdio.h>
#include <math.h>
int Check_Armstrong (int);
int main()
{
int Number,Reminder,Reverse,Temp, Sum;
int Minimum,Maximum;
printf("\nPlease Enter the Minimum & Maximum Values\n");
scanf("%d %d",&Minimum, &Maximum);
printf("Armstrong Numbers Between %d and %d are:\n",Minimum, Maximum);
for(Number = Minimum; Number <= Maximum; Number++)
{
Sum = Check_Armstrong (Number);
if(Number == Sum)
printf("%d ",Number);
}
return 0;
}
int Check_Armstrong (int Number)
{
int Temp, Reminder, Times =0, Sum = 0;
Temp = Number;
while (Temp != 0)
{
Times = Times + 1;
Temp = Temp / 10;
}
for(Temp = Number; Temp > 0; Temp = Temp /10 )
{
Reminder = Temp %10;
Sum = Sum + pow(Reminder, Times);
}
return Sum;
}
OUTPUT
ANALYSIS:
This program allows the user to enter minimum and maximum values.
for (Number=Minimum; Number<=Maximum; Number++)
This For Loop helps compiler to iterate between Minimum and Maximum Variables, iteration starts at the Minimum and then it will not exceed Maximum variable.
if(Number==Sum) -– condition will check whether the iteration number is exactly equal to Reverse number or not. If this condition is True, then it is Armstrong else the given number is not Armstrong number.
If this condition is True then, below statement will be printed
printf("%d ",Number);
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