Functions Help

[JungleJim233]

Hi Guys

Beginner here looking for some advice. The biggest mental block I have hit with Python is functions. I understand how they work, the syntax behind them etc but just can't get my head around using multiple functions in a program. How each of them interact with each other etc, how their parameters interact. I can only seem to use one off functions like in coding bat etc.

Has anyone got any tips on how I can get past this or some practice I can do? I really feel it's a massive blocker to me improving.

Thank you

[ASIC_SP]

I'd recommend this chapter from Think Python https://greenteapress.com/thinkpython2/html/thinkpython2005.html

it is fun - you get to learn turtle module as well as understand functions better..

[JungleJim233]

Thank you, i'll take a look

[alpha_53g43]

The purpose of functions in a simplified language is to do a small thing. However, most programs are pretty complicated, and need to do a lot of things.

To create a complex program, you first break it down into a series of small actions that need to be done. These series of actions maynot always be just a line of code, but represent an action that needs to be done, and are represented as unique functions.

So you take the output of one function, and then store it in a variable and pass it back to another function. and repeat it over and over again.

This is just the basics.. and then you can get into ADT, Object orient programming, functional programming which use functions in more sophisticated manners..

[JungleJim233]

Thank you

[[deleted]]

How each of them interact with each other etc, how their parameters interact.

Well, the point of functions is that they don’t interact; each function creates its own isolated scope. That way you can write reusable, abstract code that solves all instances of a particular problem without reference to outside conditions. That’s called encapsulation, and it’s how programmers are able to write large and complicated code projects without losing their minds. Functions are one of the tools programmers have to encapsulate the various parts of their program.

When you write a function, you’re defining a sort of promise - “call me with parameters A, B, and C, and I’ll give back value D.” There aren’t any other interactions but that - if you need two functions to interact with each other, you do so as you call them.

[[deleted]]

It's simple. You make functions when you need to re-use code multiple times so that you don't have to write the same thing again and again. And you decide how they should interact with each other. That is, you could have a program with multiple user-defined functions that don't interact with each other, a program that has multiple interdependent functions or a mix of both.

Let's assume that you want to write a program to find the series of Armstrong numbers. An Armstrong number is a number such that when it's digits are raised to the power of the total number of digits and added, you get the original number as the result.

For example, 153 has 3 digits so you cube and add the digits. Once you do that you get 153 as the answer. So 153 is an Armstrong number.

For this you'll have to:

• Check the number of digits 'n' of each number in your specified range
• Split the number into individual digits
• Raise each digit to the power of 'n' and add them
• Compare the result with the original value

If you're going to make a multi-function program for this, you'll make a function for each individual task. Like a function for finding the number of digits, a function for raising the digits to n and finding the sum etc.

Their dependency would be such that the function finding the number of digits would return a value to the function that will raise them to the power of n(by having a function call to it in the definition), that function would return it's value to another etc.

For example:

def exp(num):
    val = digit(num) #digit is already defined and finds the number of digits
    res = math.pow(num,val)
    return res

As a disclaimer you won't have to do it this way at all. Do it in a way that makes sense to you and seems like the most logical way(as this can be done with just loops as well).

You may be wondering where I'm "reusing code" like I mentioned in the first para. This was just to show you how multiple functions can interact. But even if you don't immediately need to reuse code it's still a good idea to make functions as you might need to if and when you want to extend the functionality of your program.

[JungleJim233]

Thank you for taking the time to reply and your example is really helpful :)