Introduction to Programming

Computer Instructions

• A computer doesn’t understand code like humans do.
• It understands basic instructions called machine code.
• A computer’s CPU handles its instructions and calculations.
• Machine code is a language that enables fast execution. It can be regarded as the lowest level source code.

What Is Programming?

• Programs

  • Programs are lists of instructions the computer performs in sequential order.
  • They typically include mathematical operations.

• Source Code

  • A program written in a high-level programming language

• A programming language includes a set of instructions that yield various types of results.

What Is Python?

• A high-level programming language
• Easy to deploy and learn
• Python’s design emphasizes code readability.
• Python is not meant for low-level programming.

Python vs. Other Languages

• Python

  • Easy to learn
  • Works in any environment
  • Many libraries
  • Large community
  • Many frameworks

• C#

  • Hard to learn
  • Works in specific environments
  • .NET libraries
  • Large community
  • .NET framework

• Java

  • Hard to learn
  • Works in any environment
  • Few libraries
  • Large community
  • Syntax is easy to learn Syntax is difficult to learn Syntax is difficult to learn
  • Many frameworks

Python Interpreter

• Python is an interpreter language.
• Reads instructions from top to bottom and left to right, with exceptions
• Performs instruction validation
• Results are returned per instruction, in sequential order.
• The interpreter can be run from within CLI using the py command or installed in the IDE.

Compiler vs. Interpreter

• Compiler Interpreter

  • It takes more time to compile; however, the code execution is faster.
  • The code is compiled for a specific operating system.
  • The source code is typically unavailable, and the compiled data can be read.
  • Once the binary is compiled, the source code is no longer needed.

• Interpreter

  • Execution takes more time, and each instruction must be compiled in real time.
  • Code can be executed in any environment that includes the interpreter.
  • The source code is available and readable.
  • The code is needed each time the program is executed.

Python 2 vs. Python 3

• Python 2

  • Python 2 code is considered legacy code.
  • Many older libraries built for Python 2 are not forward-compatible.
  • Strings are stored as ASCII characters by default.
  • Calculations are rounded to the nearest whole number.
  • Print “Hello”

• Python 3

  • Python 3 replaced Python2 at the beginning of 2020.
  • Most new libraries are being developed strictly for use with Python 3.
  • Strings are stored as Unicode characters by default.
  • Calculations are not automatically rounded.
  • Print(“Hello”)

Python Types

• CPython is the original implementation of Python.
• Jython is an implementation of Python designed to run on the Java platform.
• IronPython is an implementation of Python that can be integrated into the .NET framework.

Python Installation

Python Website

• Simple installation process
• The website where you can download Python is Python.
• Python 3 includes better support for development.

Installation Process

• Python installation for Windows is the same as any other installation.
• By default, Python 3 is installed in the AppData directory.
• It is recommended to add Python to the path.

Python in CLI

• Running the Python CLI interpreter in Windows is done using the CMD, by adding Python to the path.
• Running either py or python3 launches the interpreter.

Python IDE

Working with IDE

• Integrated Development Environment
• A program dedicated to specific software development
• IDE is easier to use than CLI.
• Includes many useful tools for software development
• One of the most useful IDE programs is PyCharm, which is used for Python programming.

IDLE

• Python’s Integrated Development and Learning Environment (IDLE)
• IDLE has two main windows: one for Shell and the other for editing.
• IDLE is a cross-platform program that works on Windows, UNIX, and macOS.

Pycharm

• PyCharm was developed by JetBrains.
• Free community version: Pycharm
• Simple Windows installation, with some required configuration

Python Environment & PyCharm

New Project

• During development, treat a program like a project.
• Projects help organize files and create a dedicated environment.
• Projects are created using the New Project option.

PyCharm Settings

• PyCharm visual themes can be extensively configured.
• Most default settings can be left as is, but some require selection.

Interpreter Configuration

• PyCharm allows selection of different interpreters for different projects.
• Python installation should be automatically detected.
• Configuration is done via Settings > Project Interpreter.

PyCharm Virtual Environment

• PyCharm allows virtual environment tools to create isolated projects.
• The purpose of a virtual environment is to manage all project settings.
• Virtual environment creation is relatively easy.

PyCharm Code Execution

• PyCharm has several ways to execute code.
• After execution, the console will appear with the results and errors.
• The console informs the developer if there are mistakes in the code.

Basic Syntax

Python Data Types

• String
• Integer
• Float
• Boolean

Python Syntax

#This is a comment
print("Hello World!")
#prints Hello World!
"""
This is how
a multi-line string
Comment looks.
"""

• Hashtag (#) renders an entire line as a comment.
• Three quotation marks (""") are used in the beginning and end of multi-line comments.
• Three quotation marks can be used in print() to print multi-line strings.

Standard Syntax Principles

number = 1
number = number + 5
#add 5 to number
print("Hello World!")

• Most programing languages are case-sensitive.
• Statements must be fully written.
• Case-sensitive means that x is not the same as X, and John is not john.

Code Handling

def main():
print("Main function")
print("Second line")
main()
class = 5
#this variable name cannot be used and will trigger an error

• Whitespace: Invisible characters that make the code more readable
• Keywords: Python’s reserved words and instructions
• Indentation: A mechanism that associates a block of code with a condition, loop, or class