= " "
()
By now, you should have sufficient knowledge and skills to accomplish this task. When done, iterate on it as long as you like. Change variable names and values. Hone on your new skills!
4 Wrapping Up Chapter Two
In chapter two, we have accomplished the following:
1) Learned what a variable is;
2) Created our first variable;
3) Learned how to display variable values.
5 Chapter Two Test
1. What is the purpose of variables?
1) Computers use variables to store information.
2) Computers use variables to change information.
3) Computers use variables to retrieve or delete information.
2. If a variable name consists of two or more words, you shall connect them using:
1) Underscore.
2) Dash line.
3) Write the words together, without space.
4) Write the words together with a capital letter without space.
3. We can display a variable on the screen by:
1) Using the print() function and passing the print command in its parentheses.
2) Using the print() function and passing the value of the variable in its parentheses.
3) Using the print() function and passing the name of the variable in its parentheses.
4. Arrange the parts of the code so that the program creates and displays the variable.
(name)
name
=
"John Doe"
CHAPTER THREE: NUMBERS
1 Integers and Fractional Numbers
You already know that integers, like 5 or 10, and fractional numbers, like 5.5 or 10.7, also called float from your school math classes. Python works with both types of numbers. It also works with relevant math operators, which are coming further.
2 Math operators
Python allows you to work with numbers using relevant math operators, that are:
1) Addition operator: +
2) Subtraction operator: -
3) Multiplication operator: *
4) Division operator: /
Let's jump into the console to work with some numbers and math operators.
3 Working with Numbers
Run empty console and hit repl button, which you already know. You should get an empty input field: input 2+2, and hit enter. What's the number you've got? Now, using the same field, subtract 5 out of 10, using subtraction operator: – Let's also multiply 5 by 5, using the multiplication operator: * Finally, let's divide 10 by 2, using the division operator: /
4 Division Without Remainder
Let's talk about division without remainder in Python. Did you notice that we've got a fraction when we divided 10 by 2, which was 5.0? But what if we need to get an integer? To get that, all we need is to use a double division operator – // Try it out. Open the input field, write 10//2, and hit enter. What number have you got now?
5 Calculation Order
Python handles calculation order, which has no difference from the order you've learned in math classes. Can you calculate (5+5)*3, then write it into the input field and check if you were right? Here is how Python will calculate it:
First, Python will calculate whatever is in brackets, following the order: first multiplication, then division, then addition, then subtraction. After that, Python will calculate whatever is around brackets, following the same order as above (multiplication, division, addition, subtraction)
Hence, Python will add 5 and 5, which will result in 10. And multiply 10 by 3, which will result in 30. Was your answer – 30? Or was it something else?)
6 Numbers and Variables
By this time, we've learned print function, variables, and numbers in Python. Let's combine them all!
Let's write an example with numbers, save its result in a variable, and then display it. Here is how it looks like:
result = 2+2
print(result)
Guess what the output will be? Please take the above code and run it in the console to check it out.
Let's break it down:
1) First, we declared a variable, giving it the name "result" and the value "1 + 1";
2) Then we went down one line, wrote the print function, and passed the name of our variable in its brackets;
3) When we ran the code, Python calculated the value of the variable by adding 2 + 2;
4) The calculation returned 4, and Python assigned this value to the variable "result";
5) Then Python saw that we want to display the result's value because of the print (result) and print it accordingly.
As you can see, numbers and variables work well together in Python.
Let's practice some more and create your examples with numbers and variables, similar to what we just saw. Here are some boilerplate examples for you:
___________
result = 2+2
print(result)
___________
result = 10-5
print(result)
___________
result = 5*5
print(result)
___________
result = 10/2
print(result)
___________
7 Wrapping Up Chapter Three
In chapter three, we have accomplished the following:
1) Refreshed on what are integers and fractional numbers;
2) Learned basic math operators used in Python;
3) Learned how to divide a number without remainder in Python;
4) Got to know the order of calculation in Python;
5) Combined numbers and variables in math examples.
8 Chapter Three Test
1. What types of numbers are there in Python?
1) There are three types of numbers in Python: Integers, almost whole numbers, and fractional.
2) There are two types of numbers in Python: Integers and half integers.
3) There are two types of numbers in Python: Integers – integer and fractional numbers.
2. How does Python divide 10 by 5? (Multiple selection)
1) 10:5
2) 10/5
3) 10-5
4) 10 * 5
5) 10 // 5
3. Arrange the parts of the code so that you get the integer 4.
five
10*2
//
4. This code should display 5. But what is missing?
result = 10/2
_____(result)
CHAPTER FOUR: STRINGS
1 Strings in Python
Do you remember the messages we displayed in chapter one, like "Hey! This is my first line of code!" or "Once upon a time.." They are all strings. In other words, a string is a data type that has a text format, or just a text, enclosed in quotes. Hence, to create a string, we have to type a text and enclose it in quotes.
2 Strings And Print Function
Let's write a code that would display the string – "Now I know what a string is in Python." You already know how to display strings in Python, right? Here is the code.
print("Now I know what a string is in Python.")
Write the above line into the console and hit run. Now it's your turn. Think of some different string, rewrite and run the above code.
3 Saving Strings in Variables
Do you remember our first variable: film = "Super Cat"? Now you know that the value of the variable – "Super Cat" had a string format, as we enclose it in quotes. Let's take our knowledge further, create a message in a string format, save it in a variable, and display the variable value on your screen using the print function. Let me do it first:
message = "Hello, Super Cat!"
print(message)
Run this code in the console. What do you see? Now it's your turn. Following the above example, think of any message. Right it down as a string. Save it in a variable and display the variable value using the print function. What you've got?
4 Strings Concatenation
We can combine strings. There is a method for that, called – concatenation. All we have to do to concatenate strings is to put addition operator + between them. Easy right? If so, let's get concatenating!
"Super Cat" + "saves the day!"
Now, let's display the two concatenated strings:
print("Super Cat" + "saves the day!")
Write this code into the console and hit run. Have you noticed something weird? Hmm. It looks like our lines stuck together. No worries. We can quickly fix that. There are several ways to do it but let's stick with the most simple – leave a space between the quote and string:
print("Super Cat" +" saves the day!")
Have you fixed that? Hit run again.
5 Strings Concatenation And Variables
Note that we can concatenate a string only with another string. Or a string-formatted value. For example, if we created a variable and assigned a string-formatted value to it, we can also concatenate such a variable with another string. In the example below, I created a variable (hero) and assigned a string-formatted value (Super Cat) to it. Then I displayed this value in concatenation with another string (VS Duper Dog).
hero = "Super Cat"
print(hero + " VS Duper Dog")
Try this code out. What message do you get? Now, change the code as you like. You can even concatenate more than two strings! Alter and run the code. See how the output changes!
6 String Formatting
Now let's talk about what string formatting is. We have already learned how to concatenate strings using the + operator. The + operator can only concatenate a string with another string. But what if we want to concatenate a string with something that doesn't have a string format? In this case, we use string formatting to turn a value that doesn't have a string format into a string-formatted value. To do so, we need two things:
The format() method to format the non-string value and insert it inside the string's placeholder.
The placeholder itself – {} for the non-string value.
Let me show you how it works in the example below:
print("My name is Super Cat, and I'm {} years old".format(2))
Please write this code into the console and run it. Here is the result you should get:
Now let's break it down.
1) We created a placeholder in our string. You can identify it by the curly brackets – {}. This placeholder is for the age of the Super Cat, which has a numeric value.
2) After the string end, we put the format() method and passed our numeric value, 2, to its brackets.
3) As a result of this operation, Python took our numeric value, formatted it into a string value, and passed it to the placeholder. So now it belongs to the entire string in the same string format.
4) After that, we displayed the entire string using the print function.
I encourage you to play with the given code and experiment with placeholders and values you pass to the format() method. Here is another way to accomplish the above exercise:
print("My name is {}, and I'm {} years old". format("Super Cat",2)
Can you explain how it works now? Can you come out with your ideas?
7 Wrapping Up Chapter Four
In chapter four, we have accomplished the following:
1) Learned what are strings in Python;
2) Learned how to store a string in a variable;
3) Learned how to concatenate strings;
4) Learned how to concatenate strings with variables values;
5) Leaned string formatting.
8 Chapter Four Test
1. What is a string?
1) A string is a line that goes through the code.
2) A string is text data enclosed in quotes.
3) A string is an integer formatted value.
4) A string is a float formatted value.
2. How do we create a string?
1) We write a text and enclose it in curly braces.
2) We write a text and enclose it in parentheses.
3) We write a text and enclose it and enclose it in quotes.
3. Arrange the code so that you get a variable with a value as a string. And then display the value of the variable on the screen.
(message)
message
"Hello, John Doe!"
=
CHAPTER FIVE: BOOLEANS
1 Comparison Operators
When we compare numbers to each other, we usually use the symbols like > (greater), < (less), = (equal), and so on. They work in Python too. And here's how they look:
Greater >
Less <
Equal ==
Not equal !=
Greater than or equal > =
Less than or equal <=
As you noticed, instead of the equal sign =, we need to use the double equal sign ==.
We need the double equal sign so that Python doesn't think we are trying to create a variable.
These symbols are called comparison operators in Python. And we need them to let our program compare different data, for instance: numbers, strings, variables, etc.
2 True or False
Boolean logic has Boolean values: True and False: True – when the condition is true. False – when the condition is false. Let's play! I will compare numbers, and you will answer in your head – True if it is true, or False if it is false. Let's go!
2 > 4
10 < 20
3 == 3
5 != 7
Now, let's check yourself. Run the console and hit the REPL button. Then, input the above comparisons into the input field, one by one, and hit enter. If your comparison is correct, the program will respond: True. If not, then False. Let's see how the examples above look in the console:
See that? This is how Boolean logic and values work. But what if we try comparing strings? Try comparing apples to oranges using the following:
"apples" == "oranges"
See the output? Now, try changing comparison operators and values to your liking. See what happens? Now you know that Boolean logic works not only with numeric but with other data formats in programming.
3 True and False in Variables
Let us see how we can use True and False values in variables. We can store results from comparisons that return True or False in variables. This is how it works:
result = "apples" == "oranges"