Python 101

May 10, 2020   Python

python

Python apart from it being a reptile, it is also a pen-testers best friend, reason being it aids in automation of your day to day pen testing activities.

Python is an interpreted high level programming language. And its a beginner language because is more of  English e.g print("I love coffee")

the above statement is a python snippet, let me break it down

print     - Its a function in python for displaying on the terminal.

( )          - Used to enclose the contents to be printed. in python 3.x is mandatory unlike python 2.x (discontinued) which wasn't.

" "         - Encloses a string to be displayed on the terminal.

If you are using windows operating system you can have python installed by browsing to https://www.python.org/ to download the latest version of python which is python 3.8.2  and if you are a Linux user python is already pre-installed.

Basics

By typing in the terminal python, you will get a prompt like this:-

python prompt

in the prompt type print("hello world" )  and you get  hello world  as the output.

hello world

you can also execute python code by saving the file ending in .py extension and execute it from the terminal with the command python hello.py.

script hello.py

Variables

Variables are data containers, which are declared by assigning values to them.

x = 10
name = "aimsec"
price = 99.9

try it on your python prompt.

variables

in order for us to see the data held in the variables we use the print function.

printing variables

Data Types

Data type is simply a classification of the value or data a variable contains, we have various data types:-

• Strings - str (This are a chain of characters) e.g x = str(" aimsec ")
• Integer - int (This are 4 byte numerical values) e.g x = int(43)
• Float - float (This are 4 byte decimal values) e.g x = float(9.99)
• Boolean - bool (This contains either True or False)

e.g isLate = True      
 print(bool(isLate))

boolean

Operators

Operators are used to perform operations on variables and values. Operators are classified into various categories:-

• Arithmetic operators
• Assignment operators
• Comparison operators
• Logical operators
• Identity operators
• Membership operators

Arithmetic Operators.

Are used to perform mathematical functions 

Operator	Name	Example
+	addition	x + y
-	subtraction	x - y
*	multiplication	x * y
/	division	x /y
%	modulus	x % y
**	Exponentiation	x ** y

Assignment Operators.

Are used to assign values to variables.

Operator	Example	Equivalent
=	x = 5	x = 5
+=	x += 5	x = x + 5
- =	x - = 5	x = x - 5
* =	x * = 5	x = x * 5
/ =	x / = 5	x = x / 5

Comparison Operators.

This operators are used to compare two values.

Operator	Name	Example
==	equal	x == y
!=	not equal	x != y
>	greater than	x > y
<	lesser than	x < y
<=	lesser than or equal to	x <= y
>=	greater than or equal to	x >= y

Logical Operators.

This operators are used in combining conditional statements.

Operator	Description	Example
and	returns true if both of the statements are true	x < 1 and y < 10
or	returns true if one of the statements is true	x < 1 or y < 10
not	returns false if the result is true	not (x < 1 and y < 10)

Identity Operators.

This operators compare objects which are similar on the same memory location.

Operator	Description	Example
is	returns true if both variables are the same object	x is y
is not	returns true is both variables are not the same object	x is not y

Membership Operators.

This operators are used to test whether a sequence is present in an object.

Operator	Description	Example
in	returns true if a sequence with the specified value is present in the object	x in y
not in	returns true if a sequence with the specified value is not present in the object	x not in y

And That's all for today guys, keep practicing on this as tomorrow will be looking into lists, tuples, sets and dictionaries.

Exercise: Create a python script that prints your name, age, and your favorite color. ADIOS!