01 Python Basics

Python Programming

Lesson 1: Python Basics

Using Python​

​Python runs in an Integrated Development Environment (IDLE)

Python provides a Python Shell, which can be used to execute single Python commands and display the result.

​Creating Programs

​We need to create a new file to write our Python programs.

This will be a blank text file which is saved as a .py document (a Python file type)

​Print & Comments

• ​The print() function will display a message to the shell

• ​The message to be printed needs to be in brackets surrounded by quotes

• ​Double or single quotes can be used, but it is important to remain consistent!

• ​Comments in Python begin with the # character.

​

Before we can run Python code, we must first save the file.

Run the code by selecting Run>Run Module from the menu.

Multiple Choice

Which function outputs text to the terminal?

• write()

• print()

• output()

• type()

​Variables

• ​We need to create variables to store values

• In Python, we assign variables by using the equals sign =

• Variables cannot have any spaces or symbols in their names other than an underscore.

• Variable names cannot being with numbers, but they can have numbers after the first letter.

• In Python, we do not have to specify a data type for our variables when we declare them.

• The basic data type are int, float and string

Multiple Choice

Which of the following will produce a Syntax Error?

• answer = "This is an error"

• answer = this_is_an_error

• answer = "This is an error'

• All of them

Multiple Choice

What is the Python syntax for creating a variable and assigning the number 10 to it?

• def variable_name = 10

• variable_name == 10

• variable_name = 10

• int variable_name = 10

Multiple Choice

Which character is used to specify a comment in Python?

• "

• *

• /

• #

​Arithmetic Operations

• ​When we perform division, the result has a decimal place.

• This is because Python converts all ints to floats before performing division.

• In older versions of Python (2.7 and earlier) this conversion did not happen and integer division would always round down to the nearest integer.

• Performing arithmetic does not change the value of a variable, you can only update values using the = sign.

Multiple Choice

What will get printed if we run this code?

• 6

• 10

Multiple Choice

Now what will get printed?

• 6

• 10

​String Concatenation

• ​The + operator does not just add two numbers

• It can also “add” two strings

• The process of combining two strings is called string concatenation

• Performing string concatenation creates a brand new string comprised of the first string’s contents followed by the second string’s contents

​Concatenation does not include spaces between the strings!

​str()

• ​To concatenate a string with a number, we need to convert the number into a string first.

• We do this using the str() function.

• We do not need to convert a number to a string for it to be an argument in a print statement.

Multiple Choice

How do you combine two strings?

• string1.concatenate(string2)

• string1.string2

• string1.combine(string2)

• string1 + string2

​Plus Equals

• ​Python offers a shorthand for updating variables.

• When you have a number saved in a variable and want to add to the current value of the variable, you can use the += (plus-equals) operator.

• We can also use the plus-equals operator for string concatenation.

Multiple Choice

What is the value of total_cost that gets printed?

• 15

• 10

• 5

​User Input

• ​We can output a value using print()

• We can assign data to a variable using input()

• The input() function requires a prompt message, which it will print out for the user before they enter their data.

• ​For example:

• ​Python always accepts user input as a string!

Multiple Choice

What is printed when we run this code if the user enters the values 5 and 6?

• 11

• 56

​Strings to Ints

• ​If we want to work with numbers, for example integers, we need to convert the users input to an integer.

• ​We can do this using the int() function.

• ​Now the program will work as expected.

Multiple Choice

What is the output of this code?

• 210

• 42

• cool_number

Multiple Choice

What happens if you run this code?

• "message" is printed

• "What a cool message!" is printed

• Python throws a SyntaxError

​Exercise 1

• ​ASCII art is a graphic design technique that consists of pictures made up of individual characters.

• ​Write a Python program called initials.py that displays the initials of your name in block letters.

ascii-art - Replit

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LovelyLoveseats - Replit

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