Python 101: Introduction to Modern Python
Tags: beginners, python
Published: 2022-02-08 18:33:16

Did you know that python is the most rapidly growing programing language? Did you know you can build web applications, games, consoles, and more using python?
python has become a world famous and powerful programming language and has been ranked the best in the year 2022. It's friendly, simple, and easy to learn.

## What is python?
Python is an interpreted, general, high-level programming language invented by Guido van Rossum and was conceived in the late 1980s and released in 1991.
## What makes it simple?
since its syntax emphasizes readability thus easy and simple to read and write.

###Sample code
printing `hello world` on the console in java and python
java:

```
public class HelloWorld{
  public static void main(String[] args){
    System.out.println("Hello World");
  }
}
```
python:
`print("Hello World")`

#What next?
Let's get started with checking if python is installed in your system. run `python` on your terminal or cmd.
if the output is similar to the one below then its installed otherwise we will need to install it.

```
Python 3.10.0 (tags/v3.10.0:b494f59, Oct  4 2021, 19:00:18) [MSC v.1929 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>>
```

##Python installation steps

1. Visit [https://www.python.org/downloads/](https://www.python.org/downloads/)
2. Select your Operating system([Windows](https://www.python.org/downloads/windows),[Linux/UNIX](https://www.python.org/downloads/source),[MacOS](https://www.python.org/downloads/macos),[Other](https://www.python.org/download/other)
3. Select the release or version, click on it to download.
4. Double click on the file to execute and install.
For window mark "add to system paths"
An alternative way to install python on Linux is to run `sudo apt install python3` or `sudo apt install python` on the terminal.

For more check on the [python documentation](https://docs.python.org/3) for more documentations.
##Let's test our installed python

1. Open Terminal on Linux or cmd on windows
2. Run the `python --version` command to check if you installed the correct version.
if python is installed, the output will be similar to as below:

```
C:\Users\jeff>python --version
Python 3.10.0

C:\Users\jeff>
```
**Print `Hello World` on the terminal or cmd by typing
`python` followed by `print("Hello World")`**
Output:

```
C:\Users\jeff>python
Python 3.10.0 (tags/v3.10.0:b494f59, Oct  4 2021, 19:00:18) [MSC v.1929 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> print("Hello World")
Hello World
>>>
```
**Next read input from the user, store it in a variable, and say hi to them.**
 Declare a variable `name` and assign a value from the user using `= input("Enter your name >>> ")` as shown below.

```
>>> name = input("Enter your name : ")
Enter your name : Jeff
>>> print("Hello Mr. " + name)
Hello Mr. Jeff
>>>
```
**Performing basic mathematical operations**
Declare two-variables `number_1` and `number_2` and assign values 20 and 10 to each respectively as shown below

```
>>> number_1 = 20
>>> number_2 = 10
>>> print(number_1 + number_2)
30
>>> print(number_1 - number_2)
10
>>> print(number_1 / number_2)
2.0
>>> print(number_1 * number_2)
200
>>>
```
In the above example we declared variables such as `name`, `number_1`, and `number_2`, but what are they.
Variables are names of storage locations whose values can be changed during program execution, they store values e.g. `name` stored the value `jeff`, `number_1` stored `20` and `number_2` stored `10`.

**There are various rules for naming variables:**

1. It should not have space, `first name` is wrong but `first_name` is correct.
2. It should not contain reserved words such as `def`, `class`, etc.
3. Should not begin numbers
4. Should not contain special characters such as `,`, `.`, `!` etc.

Imagine writing 100+ lines of code, it will not be effective using the terminal. in this case, we will need a text editor such as sublime, visual studio codes, etc
To download the Visual studio code click on the [download](https://code.visualstudio.com/download) then select visual studio code that is compatible with your operating system.
To write these lines of code into a file. and a python file has an extension of `.py`.
For example, a `HelloWorld` file is saved as `HelloWorld.py`

To run this file run `python HelloWorld.py` to execute.

In python, some libraries can be imported while performing some operations e.g. `math` library for complex operations such as `sin`, `cos`, `tan`, `log`, raising to a given power, etc.

**Use case:**

```
>>> import math
>>> print(math.log(100))
4.605170185988092
>>> print(math.sin(30))
-0.9880316240928618
>>> print(math.cos(30))
0.15425144988758405
>>> print(math.tan(30))
-6.405331196646276
>>>
```

The above examples are some of the basic simple operations that can be performed in Python. Other applications such as Web development, game development, AI, Machine learning among others.