DEV Community: Erhan Kılıç

Computer Science Fundamentals: From Binary Systems to Algorithms

Erhan Kılıç — Tue, 04 Nov 2025 16:05:58 +0000

I've started taking Harvard CS50 Computer Science classes again. Since I'm at it, I figured why not write it down? Here's my new post:

Computer Science Fundamentals: From Binary Systems to Algorithms

Computer Science, While fundamentals is often perceived as a field reserved for software developers or technology experts, it's actually a discipline anyone can learn and integrate into their daily lives. At its core lies the approach to identifying, analyzing, and effectively solving a problem. This provides benefits in many areas, from acquiring new skills to bringing an analytical perspective to everyday problems. If you're looking to delve into the fundamentals of computer science, this article is for you. We'll explain the fundamental concepts for beginners and deepen the topic with practical examples.

Fundamental Structure of Computer Science: Input, Algorithm and Output

Computer science is built on three fundamental pillars: Input (data entry), Algorithm (problem-solving logic), and Output (data output). This structure is essentially based on a philosophical foundation; it proceeds through logical steps, similar to Aristotle's rules of logic. It takes a problem, breaks it down, processes each part in a logical order, and produces a result.

This approach makes the fundamentals of computer science accessible. For example, even a coffee machine operates on this principle: coffee beans and water (input), the brewing process (algorithm), and instant coffee (output). So how do computers understand and process this data? The answer lies in the binary number system.

Representing Data: Binary Systems and Transistors

Computers represent everything using the binary number system: 1 and 0. These numbers are physically implemented through transistors. Transistors, found in billions in processors, represent the states of "powered" (1, on) or "powered off" (0, off). These transitions form the basic unit of data storage and processing.

So how do simple 1s and 0s turn into complex data? Imagine representing numbers with one hand. You normally count from 1 to 5 with five fingers. But if you assign powers of two to each finger (1, 2, 4, 8, 16), you can add up to 31 in combinations. For example:

First finger (1) + Second finger (2) = 3
All fingers = 1 + 2 + 4 + 8 + 16 = 31

Computers work similarly. A single 1 or 0 bit (Binary Digit). Eight bits come together to form byte and provides 256 different possibilities (0-255). This is based on place values as in the decimal system:

In decimal system: 123 = (1 × 10²) + (2 × 10¹) + (3 × 10⁰) In binary system: 101 = (1 × 2²) + (0 × 2¹) + (1 × 2⁰) = 5

This base is used to represent numbers and also letters and colors.

Numbers, Letters, and Colors: Coding Systems

Limiting yourself to 256 possibilities is insufficient for letters. Here it is ASCII (American Standard Code for Information Interchange) comes into play. Each byte represents a character:

01000001 = 65 = 'A'
01100001 = 97 = 'a'

However, ASCII is suitable for limited alphabets like English. It is insufficient for Turkish 'ç', 'ş' or Chinese characters. To solve this problem Unicode Advanced systems such as these have been developed that cover millions of characters using 16, 24 or 32 bits.

For colors RGB The (Red-Green-Blue) model is used. Each color is represented by three bytes: Red, Green, and Blue intensities (0-255 each). This produces 256 × 256 × 256 = 16,777,216 colors. For example, pure red: (255, 0, 0). This system plays a fundamental role in everything from digital images to web design.

When learning computer science fundamentals, understanding these encodings helps you grasp how data is stored and processed.

What is an Algorithm? Detailed Instructions and Misunderstandings

Algorithm, A step-by-step solution to a problem is described. However, computers can't reason like humans; every detail must be specified. This is the most misunderstood part of computer science fundamentals. People think the algorithm is simple, but they forget that the person you're dealing with is a "dumb" machine.

Let me give an example of a dialogue between me and a friend:

I: Tell me how to brew tea as an algorithm.
My friend: Take the teapot.
I: Ok.
My friend: Fill it with water.
I: Into what?
My friend: Into the teapot of course!
I: I'm a machine, I can't judge. I just took it, but I don't know what to do with it.
My friend: Light a fire on the stove and put the kettle on.
I: Okay, but the fire is out.
My friend: From where?
I: You said to fill it with water, but you didn't say how much. It overflowed and put out the fire.

The conclusion: “Wow, do I have to plan everything down to the smallest detail?” Yes, that’s exactly what an algorithm is! In computer science fundamentals, instructions must be clear and complete.

Practical Example: Phonebook Search Algorithms

Now let's solve a problem: Find the number of "Erhan Kılıç" in a 1000-page phone book.

Linear Search Algorithm (Simple but Inefficient):

Open the notebook.
Check each page in turn.
Write down the number if you find it, otherwise move on.

This scans 1000 pages in the worst case – inefficient!

Binary Search Algorithm (Efficient):

Open the notebook from the middle page.
Is the person you're looking for on that page? If so, enter the number.
If not, in alphabetical order (e.g. for the letter E): If you passed, discard the right side, if not, discard the left side.
Turn to the center page with the remaining notebook, repeat.

This method makes the search logarithmic – a maximum of 10 steps in a 1000 page notebook!

Try it yourself: Apply this algorithm to a book and share it in the comments. Ask any questions!

Algorithm Efficiency: Time and Complexity

The algorithm should not only be accurate, it should also be efficient. Efficiency, time complexity measured by: How does the solution time change as the problem size (n, e.g., number of pages) increases?

Linear search: O(n) – Directly proportional, graph straight line.
Binary search: O(log n) – Logarithmic, growth slows down.

Let's visualize this difference:

As the graph shows, binary search gets much faster as n gets larger.

Computer science fundamentals will improve your problem-solving skills and make your life easier. This article is an introduction, with more detailed content to come.

The Hidden Pitfall of Learning More Than One Programming Language

Erhan Kılıç — Thu, 16 Oct 2025 06:02:37 +0000

The Invisible Effect of Your Native Language

In my 12-year software development adventure, I've noticed this: Multiple programming languages When you're learning, your native language shapes your mindset. For example, the language you first learn influences how you use new languages. Often, you unknowingly write code using your native language's logic. This can make it difficult to adapt to new technologies. However, it's possible to overcome this influence!

Moving from PHP to Node.js

I first noticed this while learning Node.js. My native language PHP I had been coding in a synchronous world for years. When I switched to the asynchronous architecture of Node.js, my code was inefficient and buggy. However, Node.js official documentation When I studied PHP and learned asynchronous programming, I stepped out of PHP's shadow. This gave me a new perspective.

A New Lesson with Elasticsearch

I also experienced a similar situation when I moved from MySQL to Elasticsearch. At first, I tried to use Elasticsearch like a database: "Save data, fetch it." However, Elasticsearch's true strength lies in statistical analysis and search engine optimization. Elastic's official site It was a great guide on this subject. Therefore, understanding its logic helped me use it effectively.

5 Ways to Learn New Languages Effectively

So, how can you overcome the influence of your native language? Here are some suggestions:

Develop Awareness: For example, consider how your native language influences your coding style.
Focus on the Basics: Learn the design philosophy of the new language, such as asynchronous programming for Node.js and search engine logic for Elasticsearch.
Practice: Don't be afraid of your mistakes. Every mistake helps you understand the logic of a new language.
Take Advantage of Communities: Platforms like Stack Overflow or Open source projects on GitHub can be inspiring.
Stretch Your Mind: Ultimately, a new language is not just a tool, it's a way of thinking. Be open to letting go of old habits.

Embrace New Technologies

Ultimately, learning multiple programming languages is a necessity in the software world. However, breaking free from the influence of your native language makes this process easier. I learned this lesson when I moved from PHP to Node.js and MySQL to Elasticsearch. Try these steps to adapt to new technologies! Share your own experiences in the comments, and let's discuss them together.

Why Are E-Books More Expensive Than Printed Books?

Erhan Kılıç — Mon, 27 Aug 2018 12:09:21 +0000

Today, I saw this site on Hackernews and I shared the link with my friends. Then, I wanted to know if there was an e-book version and yes, there is. But something caught my attention. When I checked the printed version of this book, It's price is same with e-book version!! This is a complete nonsense! Sometimes e-books are more expensive than printed books!

It is logical that e-books should be cheaper than printed books. I searched on web and I found this article. Apparently, the prices of e-books are too high because of the publisher's greed!! This must be stopped!!

I prefer e-books because there is no paper consumption, access is easier, and for a lot of reasons, but all these beautiful things do not happen because of the publisher's greed.

I hope this situation will improve soon.

How To Import SQL File With PHP

Erhan Kılıç — Sun, 26 Aug 2018 16:28:47 +0000

This post was first published on How To Import SQL File With PHP

Sometimes there are times when you can not use PhpMyAdmin or any database program, and you have to use other options to import the Sql file into your database. Here, I’ll tell you how you can import with both the old mysql_query and the new mysqli_query in Php. You can also access the codes from the my Github project.

You need to do followings on both methods; upload Sql file and php file at the same place and run the php file through the site address. You can also run console commands through the server.

Update $filename with the name of sql. Update the $mysql_host variable with the database server. If the database server is not different, you can leave it as it is. $mysql_username and $mysql_password are the username and password for your database. $mysql_database is the database name, update it with your database name.

With mysql_query Function

<?php

// Name of the file
$filename = 'sql.sql';
// MySQL host
$mysql_host = 'localhost';
// MySQL username
$mysql_username = 'username';
// MySQL password
$mysql_password = 'password';
// Database name
$mysql_database = 'database';

// Connect to MySQL server
mysql_connect($mysql_host, $mysql_username, $mysql_password) or die('Error connecting to MySQL server: ' . mysql_error());
// Select database
mysql_select_db($mysql_database) or die('Error selecting MySQL database: ' . mysql_error());

// Temporary variable, used to store current query
$templine = '';
// Read in entire file
$lines = file($filename);
// Loop through each line
foreach ($lines as $line) {
// Skip it if it's a comment
    if (substr($line, 0, 2) == '--' || $line == '')
        continue;

// Add this line to the current segment
    $templine .= $line;
// If it has a semicolon at the end, it's the end of the query
    if (substr(trim($line), -1, 1) == ';') {
        // Perform the query
        mysql_query($templine) or print('Error performing query \'<strong>' . $templine . '\': ' . mysql_error() . '<br /><br />');
        // Reset temp variable to empty
        $templine = '';
    }
}
echo "Tables imported successfully";

With mysqli_query class

<?php

// Name of the file
$filename = 'sql.sql';
// MySQL host
$mysql_host = 'localhost';
// MySQL username
$mysql_username = 'username';
// MySQL password
$mysql_password = 'password';
// Database name
$mysql_database = 'database';

// Connect to MySQL server
$con = @new mysqli($mysql_host,$mysql_username,$mysql_password,$mysql_database);

// Check connection
if ($con->connect_errno) {
    echo "Failed to connect to MySQL: " . $con->connect_errno;
    echo "<br/>Error: " . $con->connect_error;
}

// Temporary variable, used to store current query
$templine = '';
// Read in entire file
$lines = file($filename);
// Loop through each line
foreach ($lines as $line) {
// Skip it if it's a comment
    if (substr($line, 0, 2) == '--' || $line == '')
        continue;

// Add this line to the current segment
    $templine .= $line;
// If it has a semicolon at the end, it's the end of the query
    if (substr(trim($line), -1, 1) == ';') {
        // Perform the query
        $con->query($templine) or print('Error performing query \'<strong>' . $templine . '\': ' . $con->error() . '<br /><br />');
        // Reset temp variable to empty
        $templine = '';
    }
}
echo "Tables imported successfully";
$con->close($con);

What do you think about Open Source Society University?

Erhan Kılıç — Fri, 17 Aug 2018 04:46:57 +0000

What do you think about Open Source Society University? OSSU is path to a free self-taught education. I wanted to know what people think about it. Do people take it serious? Do people see it equivalent to a bachelor in computer science?

My current situation is as follows;

I graduated from a vocational high school. I learned everything on my own. I want to study computer science and work abroad. If I want to go to a university in my country, I will have to learn very unnecessary things to prepare for the university exam. At the same time, the quality of education of universities in my country (Turkey) is very low and I do not think that they won't get serious in the world. On the other hand, I want to study a serious computer science. It is a difficult option to study abroad because I am 31 years old, study abroad is expensive and I have to work at the same time.

Setting Up Your Own Git Server

Erhan Kılıç — Wed, 15 Aug 2018 18:10:17 +0000

This post was first published on Setting Up Your Own Git Server

Setting up your own git server is very useful. You can set up your own git server on Vps, Vds, Dedicated servers or even on your local machine. I assume you have installed git on your Linux server.

First we need to create a git directory under the root directory. In the following code I will create a example named git server. So you can set up as many git servers as you like.

mkdir /git/example.git

Then in the terminal, go to the directory /git/example.git and write the following code.

git init --bare

That’s all!! We created our git server. If you want to clone you should write the following code;

git clone username@serveripaddress:/git/example.git

It will ask your server’s password.

If you have a local project on your computer and you want to include it in your git server, type the following code in the terminal under your project directory;

git remote add myserver username@serveripaddress:/git/example.git
git push myserver -u master

You can change “myserver” with a name whatever you want. “origin” is commonly used name.

When you send your commits with the push command, your server will ask for the user password.

If you want your server to take your commits and create your project in another directory when you send your commits, you must create a post-recived named file under the /git/example.git/hooks directory with 777 permission. why would you want such a thing? In your project, we assume that you have commands that do build operations like gulp. After sending your commits, you can want that your gulp processes run automatically and the your project will be ready. You can even have development and production branches run automatically in separate folders.

Edit the inside of post-recived file as follows.

#!/bin/bash
GIT_WORK_TREE=/home/project-directory/ git checkout -f master

You can set the directory location as you like.

If you are using something like composer, bower, you can arrange them to work as follows.

#!/bin/bash
GIT_WORK_TREE=/home/project-directory/ git checkout -f master
cd /home/project-directory/
php composer.phar update
cd /home/project-directory/
bower install

Adding Infinite Scroll Without Plugin To WordPress Theme

Erhan Kılıç — Sat, 11 Aug 2018 15:37:30 +0000

This post was first published on Adding Infinite Scroll Without Plugin To WordPress Theme

In this tutorial I will tell you how to add an infinite scroll to your WordPress theme without using the plugin. This article will be the most accurate article. Because if I have done my research to add endless scrolls myself, I have found articles that describe using plugins or methods that work in index.php but not in category.php or author.php. They did not work right on the other files. Because the sample verbs do not load in the category file according to the categorization while loading the second page and the letters of the latter. It was loading all the pages.

You can refer to the source code of AdminLteWpTheme when doing these operations. There are codes of the employee working there.

First, we add the following codes to the functions.php file;

//Infinite Scroll
function wp_infinitepaginate(){
     $loopFile = $_POST['loop_file'];
     $paged = $_POST['page_no'];
     $action = $_POST['what'];
     $value = $_POST['value'];

     if($action == 'author_name'){
         $arg = array('author_name' => $value, 'paged' => $paged, 'post_status' => 'publish');
     } elseif ($action == 'category_name'){
         $arg = array('category_name' => $value, 'paged' => $paged, 'post_status' => 'publish' );
     } elseif ($action == 'search'){
         $arg = array('s' => $value, 'paged' => $paged, 'post_status' => 'publish' );
     } else {
         $arg = array('paged' => $paged, 'post_status' => 'publish');
     }
     # Load the posts
     query_posts( $arg );
     get_template_part( $loopFile );

     exit;
}
add_action('wp_ajax_infinite_scroll', 'wp_infinitepaginate'); // for logged in user
add_action('wp_ajax_nopriv_infinite_scroll', 'wp_infinitepaginate'); // if user not logged in

When an ajax request arrives, this function will work, will generate a loop and this loop will gets our file. In our function we will receive some POST data;

“loop_file” is the name of our loop file. This file will generate html codes. Then we will append it with JavaScript.

The page number is “page_no”. We therefore determine which page we will be using.

“what” is what we want pages for. Like category, author, search etc.

“value” contains the category slug name, author nicename, etc., if the category, author, or request.

With the If query we create our parameters for query_posts according to what we want here. Then we can create a loop with query_posts and call our file with get_template_part.

With the add_functions function, we provide an ajax request to wp-admin/wp-ajax.php to run your function. We send an infinite_scroll in the action post while sending an Ajax request. So you can create different ajax operations with different names and functions.

Then we will create our loop file under our theme directory. You can give the name here as you like, but don’t forget, you should send this name in the “loop_file” post. I gave the name loop.php. Here you can copy your direct loop from index.php file. I am putting it as an example in AdminLteWpTheme here.

<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
<!-- timeline time label -->
<li class="time-label">
    <span class="bg-green"><?php the_time('d.m.Y ') ?></span>
</li>
<!-- /.timeline-label -->
<!-- timeline item -->
<li>
    <i class="fa fa-newspaper-o bg-blue"></i>
    <div class="timeline-item">
        <span class="time"><i class="fa fa-clock-o"></i> <?php the_time('H:i') ?></span>
        <h3 class="timeline-header"><a href="<?php the_permalink() ?>" alt="<?php the_title(); ?>" title="<?php the_title(); ?> "><?php the_title(); ?></a></h3>
        <div class="timeline-body">
            <div class="row">
                <div class="col-lg-3 col-sm-4 col-xs-6">
                     <a href="<?php the_permalink() ?>" title="<?php the_title(); ?>">
                     <?php $resim_yolu = wp_get_attachment_image_src( get_post_thumbnail_id(), 'medium'); if ( has_post_thumbnail() ) { ?>

                         <img src="<?php echo $resim_yolu[0]; ?>" class="img-responsive" alt="<?php the_title(); ?>" title="<?php the_title() ?>" />
                     <?php } ?>
                     </a>
                 </div>
                <div class="col-lg-9 col-sm-8 col-xs-6">
                     <?php the_excerpt_rss(); ?>
                     <div style="margin-top: 10px">
                         <a class="btn btn-primary btn-xs" href="<?php the_permalink() ?>" title="<?php the_title(); ?>">Read more</a>
                     </div>
                </div>
           </div>
       </div>
       <div class="timeline-footer">
             <i class="fa fa-user"></i> <a href="<?php echo esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ); ?>" title="<?php the_author(); ?>"><?php the_author(); ?></a> | <i class="fa fa-folder-open"></i> <?php the_category(', ') ?> | <i class="fa fa-comments"></i> <?php comments_number('0 comment', '1 comment', '% comments' );?>
         </div>
     </div>
</li>
<!-- END timeline item -->
<?php endwhile; ?>
<?php endif; ?>

Finally, we must write our JavaScript code in our files like index.php, category.php.

<script type="text/javascript">
 jQuery(document).ready(function($) {
   var count = 2;
   var total = <?php echo $wp_query->max_num_pages; ?>;
   $(window).scroll(function(){
     if ($(window).scrollTop() == $(document).height() - $(window).height()){
      if (count > total){
        return false;
      }else{
        loadArticle(count);
      }
      count++;
     }
   });

   function loadArticle(pageNumber){
     $('a#inifiniteLoader').show('fast');
     $.ajax({
       url: "<?php echo admin_url(); ?>admin-ajax.php",
       type:'POST',
       data: "action=infinite_scroll&page_no="+ pageNumber + '&loop_file=loop',
       success: function (html) {
         $('li#inifiniteLoader').hide('1000');
         $("ul.timeline").append(html);
       }
     });
     return false;
   }
 });
</script>

The Count variable is our page number. Initially it will be 2 because the second page will be uploaded when page goes down first. Each ajax will increase the variable on demand. Our Total variable is the total number of pages. In this case we will make sure that the function does not work when the page goes down.

$(window).scroll( function () {} ); function will send an ajax request when the page goes down and we will increase the count variable. Of course, we write an If condition (as long as count variable is bigger than our total variable) so code won’t work unnecessary.

With our loadarticle() function, we first make the loading icon appear, and then send the ajax request. you can review the post data by sending it. We do not forget to include what and value datas in places such as category, author. As an example, I am writing in the category.php file. You can see what and value data there.

I hope this article works for you.

<script type="text/javascript">
 jQuery(document).ready(function ($) {
   var count = 2;
   var total = <?php echo $wp_query->max_num_pages; ?>;
   $(window).scroll(function () {
     if ($(window).scrollTop() == $(document).height() - $(window).height()) {
       if (count > total) {
         return false;
       } else {
         loadArticle(count);
       }
       count++;
     }
   });

   function loadArticle(pageNumber) {
     $('a#inifiniteLoader').show('fast');
     $.ajax({
       url: "<?php echo admin_url(); ?>admin-ajax.php",
       type: 'POST',
       data: "action=infinite_scroll&page_no=" + pageNumber + '&loop_file=loop&what=category_name&value=<?php echo $yourcat->slug; ?>',
       success: function (html) {
         $('li#inifiniteLoader').hide('1000');
         $("ul.timeline").append(html);
       }
     });
     return false;
   }
 });
</script>

Making Snake Game With Javascript

Erhan Kılıç — Sat, 14 Jul 2018 17:21:21 +0000

This post was first published on Making Snake Game With Javascript

Ever since childhood I have always wondered how to make games and I wanted to make my own game one day. After spending so much time in the software industry, I asked myself why I should not do it anymore. Thus, I will improve my Javascript skill and I will also look at the software development process in a way that I have never looked at before.

Before I started coding the game, I began to think about how the algorithm of the snake's movement would be. Some of the first options that came to mind were; scan the entire playground in every move, to keep the coordinates of each cell of the snake on a array and update the old and new cells while moving. At the end, I understood that it was best to erase the last cell of the snake and attach a cell to the head.

First I created a snake object and I wrote the code that would create the playground. After creating the playground, I found a nice font for the game and added it. I wrote the algorithm that would make the snake move after I wrote a code that composes the snake and puts it into the playground.

When I wrote the snake's movement for the first time, it continued to move outside the playing field and could go back inside. For example, while the snake was moving upwards, if I pressed down, it was moving within itself.

First of all, if the snake came to the edge of the playing field, I wrote the codes that would allow it to continue from the other end. So, for example, if the snake reached the left edge, it would have entered the right edge.

After that, I wrote the codes that control the direction key that moves according to the direction the snake moves. So, for example, if I press down on the button while the snake is moving up, it doesn't do anything. After this I added the ability to start and stop the game.

At this point, I stopped taking care of for about a month or two. A lot of different thoughts and things got in.

Today the game came to mind again and I started again. Finally, I finished the game by adding the bait, the game score and the ability to manage game settings.

I enjoyed making this game very much and I am very excited to see the result. Only problem is if we press the arrow keys too fast, the snake starts to act ridiculous. I think this is caused by the frame rate of the game, but I have not figured it out yet.

My next goal is to write a tetris or a simpler than tetris.

You can play the game on here.

You can check the codes on here.

Which Programming Language To Learn?

Erhan Kılıç — Mon, 27 Nov 2017 06:34:31 +0000

Hello everyone,

I'm fullstack web developer. I know php, javascript, nodejs and learned a little go lang. I want to improve myself and learn strong typed, low level programming language but I don't know which one.

I want to learn new language because I want to learn new ways of thinking about problems and new ways of solving problems. I want to improve myself at programming. I can't feel like I'm programming or solving problems at web development anymore. I'm just doing same things at web development.

C/C++ is good option but it has lots of keyword (over 90 if I remember correctly) and it's old.

Rust is good option too. New and modern language, Mozilla develops it (I love Mozilla) and it's really favorite language at stackoverflow but it's new and doesn't have much library bla bla.

Python is good option. It has lot's of library, very well supported...

What would you do and why?

Php ZipMaster - Zip files and folders with php

Erhan Kılıç — Fri, 27 Oct 2017 07:31:27 +0000

Hello to everyone. This is my first article. If there are any mistakes, please do not look up.

Compressing files in PHP and creating a zip file is easy, but the situation changes when you include folders into the job. You may want to automatically back up the files on your server like me and you may want to have a solution for it. I have a vps with a lot of sites and I want these sites to be automatically backed up. My solution is to write a script in PHP creates a cronjob.

It is simple to use and you can use it as you like. Please do not hesitate if you want to improve.

Sample use;

<?php

include 'ZipMaster.php';

$zip = new ZipMaster\ZipMaster('backup/test.zip', 'test_folder');
$zip->archive();

You can reach the project here.