CHAPTER ONE: LET’S GET CODING!
1 Your First Line Of Code
Any, even the most advanced python program, starts with the first line of code. Here is an example of a simple program that has just one line of code. The only thing the program does is it outputs the message: "Hey! This is my first line of code!"
Open the console and write the following:
print("Hey! This is my first line of code!")
Don't worry. We'll learn what this code means in the following chapters. Now it's essential to get you going! When done, run the code by hitting the green play button. Here is the result you should get:
Well done! You've just started and have already written your first simple program.
2 What Is a Program?
Even if it was just a single line of code, we've created a program. Like those that make computers work.
But what is a program? A program is a set of instructions and rules for a computer written in a programming language. If that makes sense, let's go on and reinforce what we have learned. Here is the code I've shuffled. It will help if you put it so that it would make it work.
"Once upon a time…!" () print
If you put it right, you should get a program that prints a sentence. Here it is below.
Are you done with the task? Great! In both programs that we have just created, we used a print function. We will use it a lot in this book. But first, let's dive a little deeper into it.
3 Print Function
Print is the function that does what it's called: it "prints" text on a screen. Programmers use this function to show messages to users. Such as "Your session is expired, please log in" or "Your password is too weak, please use a stronger password," etc.
Not only simple text messages, but the print function can also display different calculation results, presented in numeric format. We will learn all this stuff in the coming chapters. For now, we will focus purely on the print function and code some more with it.
Here is the plain text for you. Please use it with the print function, so when you run the code, it shows you the following message: Hey! I keep coding! Here is what you should get:
Have some fun. Since now you have learned how to write a program that displays messages, experiment with different messages you want your program to print. Use numbers too. Try adding or removing anything from your code. And then watch what happens; This is the best way to learn how the code operates.
4 How Does Python Read The Code?
As soon as you run the code, the computer starts reading it line by line, from top to button. Just like you're reading this book or anything. It may not sound too important, but it's essential to consider it when building and arranging our code; This is why some elements like modules (we will learn them in the following chapters) belong at the top of the code. We import them first to use them further down.
5 Counting Program
Let's build a program that counts from 1 to 3. Here is the code we need to do that:
print("1")
print("2")
print("3")
Pretty simple, right? Now extend the code so that it could count to 10. Here is the result you should get when you run your extended program:
6 Python Challenge
Let's celebrate the completion of the first chapter with a small challenge. You need to complete the below line of code so that it could output the message: "I nailed the first chapter!"
Here is what the output should look like when you fix and run the program:
7 Wrapping Up Chapter One
In the first chapter, we have accomplished the following:
1) Learned what Python is;
2) Understood what a program is;
3) Found out how does Python read the code;
4) Wrote our first line of code;
5) Created a few simple programs;
6) Finally, we learned and applied the print function.
8 Chapter One Test
1. A computer program is a:
1) Set of instructions and rules for a computer, written in a programming language.
2) Piece of code written on a computer.
3) Downloadable game.
2. How do we let a computer know that it needs to display a message on the screen?
1) With a magic word.
2) Using the print() function)
3) Using the command "Display message!"
3. In what order does a computer process (read) the code?
1) When we run the code, the computer reads that code line by line. Top-down.
2) When we run the code, the computer reads that code from bottom to top.
3) When we run the code, the computer doesn't read anything; it remembers everything by heart.
4. Arrange the parts of the code so that the program displays the message "I love Python!"
)
(
"I love Python!"