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August, 2020

## Intro 🌐

Problem solving is an important skill, for your career and your life in general.

That’s why I take interesting katas of all levels, customize them and explain how to solve them.

## Understanding the Exercise❗

First, we need to understand the exercise! If you don’t understand it, you can’t solve it!.

My personal method:

1. Input: What do I put in?
2. Output: What do I want to get out?

### Today’s exercise

Source: Codewars

Write a function `positionInAlphabet`, that accepts one parameter: `myChar`.

Given a one-char string, e.g. `"a"`, return the message “Position in Alphabet: [position]”, e.g. `"Position in Alphabet: 1"`. If the input is uppercase, handle it like a lowercase character.

Input: a string.

Output: a string.

## Thinking about the Solution 💭

I think I understand the exercise (= what I put into the function and what I want to get out of it).

Now, I need the specific steps to get from input to output.

I try to do this in small baby steps:

1. Convert the character into lowercase
2. Find the position of the char in the alphabet
3. Return the desired message with the position

Example:

• Input: `"a"`
• Convert the character into lowercase: `"a"`
• Find the position of the char in the alphabet: `1`
• Return the desired message with the position: `"Position in Alphabet: 1"`
• Output: `"Position in Alphabet: 1"`

## Implementation (charCodeAt) ⛑

``````function positionInAlphabet(myChar) {
const DIFFERENCE_CHARCODE_AND_LETTERS = 96;

// Convert the character into lowercase
const myCharLowercase = myChar.toLowerCase();

// Find the position of the char in the alphabet
const position = myCharLowercase.charCodeAt() - DIFFERENCE_CHARCODE_AND_LETTERS;

// Return the desired message with the position
return `Position in Alphabet: \${position}`
}``````

Where do we get the `96` from? When we go to the ASCII Table and scroll down to the `a` in the `Char` column, we can see `97` in the `Number` column. So our `1`. char has the number `97`, our `2`. char has number `98` etc., meaning there is a difference of `96` between the char code (the `Number` column) and the actual char (the `Char` column).

### Result

``````console.log(positionInAlphabet("a"));
// 1 ✅

console.log(positionInAlphabet("Z"));
// 26  ✅``````

## Implementation (indexOf) ⛑

``````function positionInAlphabet(myChar) {
const letters = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"];

// Convert the character into lowercase
const myCharLowercase = myChar.toLowerCase();

// Find the position of the char in the alphabet
const position = letters.indexOf(myCharLowercase) + 1;

// Return the desired message with the position
return `Position in Alphabet: \${position}`;
}``````

### Result

``````console.log(positionInAlphabet("a"));
// 1 ✅

console.log(positionInAlphabet("Z"));
// 26  ✅``````

## Playground ⚽

You can play around with the code here

## Next Part ➡️

Great work!

We learned how to use `toLowerCase`, `charCodeAt`, `indexOf`.

I hope you can use your new learnings to solve problems more easily!

Next time, we’ll solve another interesting kata. Stay tuned!

If I should solve a specific kata, shoot me a message here.

If you want to read my latest stuff, get in touch with me!