# Armstrong Numbers in Python

# Check if a given number is Armstrong using Python

For starters let us understand what Armstrong numbers are?

An **Armstrong number** is a positive number which when raised to the length of its digits is equal to the original number. 
> abcd... = a^n + b^n + c^n + d^n + ...   
where n is the length of the number(abcd)

For example:
> A number 407  has a length of 3

>4^3 + 0^3 + 7^3 = 407

 from the example above 407 is an Armstrong number. All good now!!

![1694274_1.jpg](https://cdn.hashnode.com/res/hashnode/image/upload/v1594032290792/xPZmE8r2L.jpeg)

## Source Code: Check Armstrong number of n digits
Let' s dive into the fun part, writing the code. First, Create a function call armstrong()
```
def armstrong():
``` 
Using the input() function allow the user to enter an integer as input which will be stored in the variable called number:

```
 number = int(input("Enter a number: "))
``` 
To check the length of a number in python, first convert the number into a string using the inbuilt str() function and store it in the variable n. Initialize the variable total_sum to 0 as we will be calculating the sum of the raised digits:

```
 n = len(str(number))
 total_sum=0
``` 
We will introduce a control structure that will help direct the order of execution of the statements in our program, the **if ... else statement**

All numbers that have one digit or have a length of one is an Armstrong number by default. To check this we use the if statement below and return a print statement if the condition is satisfied:

```
  if len(str(number)) == 1:
        print("All single digit numbers are Armstrong numbers")        
``` 
We then check to ensure the user enters a positive number. The function then throws an exception when a negative number is entered and proceeds to call the function again so that the user can try again and enter a positive number :
```
  elif number < 0:
        print("Enter a positive number")
        armstrong()
``` 
In the Python language ecosystem, one can only loop through string data types, not integers, therefore, using the inbuilt str() function, we convert the number variable to a string so as to obtain the individual digits of the number.

First, loop through the number, assigning the digits to the variable *x*, secondly, raise the *x* to the initial variable *n*(as shown above), thirdly, add the raised digits and store them in the previously initialized variable *total_sum*
 
The code below makes use of nested if statements to print out whether the passed number is an Armstrong number or not. 
```
else:
        for x in str(number):
            total_sum += int(x)**n
        if total_sum == number:
            print("This is an Armstrong number")
        else:
            print("This is not an Armstrong number")
``` 

Here is the whole source code:
```
def armstrong():
    number = int(input("Enter a number: "))
    n = len(str(number))
    total_sum=0

    if len(str(number)) == 1:
        print("All single digit numbers are Armstrong numbers")        
    elif number < 0:
        print("Enter a positive number")
        armstrong()
    else:
        for x in str(number):
            total_sum += int(x)**n
        if total_sum == number:
            print("This is an Armstrong number")
        else:
            print("This is not an Armstrong number")

armstrong()
``` 
Here is a snippet on how the program runs on the VS code terminal:

![Capture.JPG](https://cdn.hashnode.com/res/hashnode/image/upload/v1594041377961/4q9zWmcwv.jpeg)

Thank you for reading, if you have any thoughts, get in touch in the comments section.

Here's to changing the society one code at a time. &#129346;

Have a great day Pythonistas.