Phase 1: Larn the Basics of Programming

1.1 Understanding Programming

Programming is the process of writing a set of instructions for a computer to execute. These instructions tell the computer what tasks to perform, how to process data, and how to interact with users or other systems.

1.2 The Role of a Programmer

As a programmer, you solve problems using logic and creativity. Your job is to break down a problem into small steps and express those steps in a way that a computer can follow.

1.3 Why Do We Need Programming?

Computers are incredibly fast, but they are also dumb—they only follow instructions and don’t think for themselves. Programming is what allows us to control computers and make them useful, from running websites and mobile apps to controlling robots and analyzing data.

2.1 The Language of Computers: Binary (0s and 1s)

Computers don’t understand human languages. They operate using a system called binary, which consists of just two symbols: 0 and 1. Every instruction we write must eventually be translated into this format.

2.2 From Human Language to Machine Code

To bridge the gap between humans and computers, we use different levels of programming languages:

High-Level Languages (e.g., Python, Java, JavaScript) – Easier to read and write.

Low-Level Languages (e.g., Assembly, Machine Code) – Harder to read but closer to how computers work.

A program written in a high-level language must be translated into machine code by a compiler or interpreter before the computer can execute it.

3.1 Algorithmic Thinking

An algorithm is a step-by-step set of instructions designed to solve a problem.

Example of an Algorithm (Making a Sandwich)

1. Take two slices of bread.
2. Spread peanut butter on one slice.
3. Spread jelly on the other slice.
4. Put the slices together.
5. Serve.

This process is an algorithm because it has clear, repeatable steps that achieve a goal.

3.2 Decomposition: Breaking Down Problems

Programmers solve problems by breaking them into smaller, more manageable pieces. This approach is called decomposition.

Example:

If you were to build a calculator app, you wouldn’t start by writing the whole program at once. Instead, you’d break it down:

1. How will the program receive input?
2. How will the program process different operations?
3. How will the program display the results?

By solving these smaller problems individually, the overall program becomes easier to build and maintain.

3.3 Debugging: Fixing Mistakes in Code

Programs often don’t work correctly on the first try. Debugging is the process of finding and fixing errors in a program.

There are different types of errors:

Syntax Errors – When instructions are written incorrectly.

Logical Errors – When the program runs but produces incorrect results.

Runtime Errors– When the program crashes while running.

To debug effectively, programmers use trial and error, error messages, and testing strategies to identify what went wrong.

4.1 What are Variables?

A variable is a way to store and reference information in a program. It acts like a labeled container that holds data.

Example:

A shopping cart stores items.

A bank account stores money.

A variable stores a piece of information.

4.2 Types of Data in Programming

Different types of data can be stored in variables:

Numbers (whole numbers, decimals)

Text (Strings) (words, sentences)

Boolean Values (True/False)

Each piece of data behaves differently in a program.

Example:

A number can be used in math operations (e.g., addition, subtraction).

Text can be displayed or modified (e.g., changing a name from "John" to "Johnny").

5.1 What is Input?

Input is any data that the program receives from an external source, such as:

A user typing on a keyboard.

A file being read.

A sensor providing real-world data (e.g., temperature readings).

5.2 What is Output?

Output is the information that a program sends out, such as:

Displaying text on a screen.

Writing data to a file.

Sending messages to another system.

Input and output allow programs to interact with the world and respond to users.

6.1 What are Conditional Statements?

Conditional statements allow programs to make decisions based on certain conditions.

Example in Real Life:

"If it is raining, take an umbrella."

A program can follow the same logic:

1. Check if the condition is true.
2. Execute the appropriate action.

6.2 Logical Operators

Conditional logic relies on comparison operators like:

Equal to (==)

Greater than (>)

Less than (<)

Programs also use logical operators:

AND (both conditions must be true).

OR (at least one condition must be true)

NOT (negates a condition).

7.1 Why Do We Need Loops?

Loops allow a program to repeat actions without writing the same instruction multiple times.

Example in Real Life:

Imagine you’re washing dishes. Instead of saying:

1. Pick up a plate.
2. Scrub the plate.
3. Rinse the plate.
4. Dry the plate.
5. Pick up another plate.
6. Scrub the plate… (and repeating for every plate!)

A loop allows you to say:

"While there are still dirty plates, repeat the process: pick up, scrub, rinse, dry."

7.2 Types of Loops

Definite Loops (repeat a fixed number of times).

Indefinite Loops (repeat until a certain condition is met).

7.2.1 Definite Loops (Fixed Repetition)

A definite loop is used when we know in advance how many times something should repeat.

Example in Real Life:

You want to send a thank-you message to 10 friends.

Instead of writing 10 separate instructions, a loop can repeat the task exactly 10 times.

7.2.2 Indefinite Loops (Repeat Until Condition is Met)

An indefinite loop keeps running until a certain condition is met.

Example in Real Life:

You are waiting for a taxi.

You keep checking the road until a taxi arrives.

Once a taxi arrives, you stop checking and get in.

7.2.3 Infinite Loops (Caution!)

An infinite loop happens when the loop never stops running. This is usually a mistake.

Example in Real Life:

Imagine you are watching a playlist of videos, but instead of stopping after the last video, it keeps replaying forever!

To prevent infinite loops, we must ensure that there is always a way to exit the loop.

7.3 Nested Loops (Loops Inside Loops)

Sometimes, we need a loop inside another loop.

Example in Real Life:

You know you wrote someones birthday on your calendar and are trying to find it, but you have no idea what month or day it is.

You look through every month (First loop) and then every day (Second loop).

7.5 When to Use Loops?

When repeating tasks multiple times (e.g., processing 100 files).

When waiting for a condition to change (e.g., waiting for user input).

When iterating over large amounts of data (e.g., analyzing customer orders).

8.1 What are Functions?

Functions are reusable blocks of code that perform specific tasks.

Example in Real Life:

A microwave has a "Popcorn" button that runs a specific set of instructions every time you press it.

8.2 Why Use Functions?

Avoid repetition (write code once, use it multiple times).

Improve readability (break down complex logic into smaller parts).

9.1 Why Do We Need Data Structures?

A data structure is a way of organizing and storing data so that it can be used efficiently.

Think of data structures as containers for storing different types of information

9.2 Common Data Structures

Lists/Arrays – Store multiple items in order.

Dictionaries/Maps – Store key-value pairs for quick lookups.

Sets – Store unique items only.

9.3 Lists and Arrays (Ordered Collections of Data)

A list (or array) is a collection of items stored in order.

Example in Real Life:

A to-do list keeps track of tasks in order.

A queue in a store keeps people in order.

Lists/arrays allow us to:

Add new items.

Access specific items by their position.

Modify existing items.

9.4 Dictionaries and Key-Value Pairs (Mappings)

A ictionary (or map)d stores pairs of data, where each item has a key and a value.

Example in Real Life:

A phone book stores names (keys) and phone numbers (values).

A word dictionary stores words (keys) and definitions (values).

9.5 Sets (Unique Collections of Data)

A set is a collection of unique items. It does not allow duplicates.

Example in Real Life:

A guest list for a party (each person’s name appears only once).

A deck of cards (each card appears only once).

9.6 Choosing the Right Data Structure

Each item in Lists/Arrays has a position (index) that lets us access it easily.

Dictionaries allow fast lookups because we can find data based on a unique key, rather than searching through a list.

Sets are useful when we need to avoid duplicates and focus only on unique values.