Python is one of the most popular programming languages out there today. The core philosophy of Python is summarised in the Zen of Python which contains the guiding principles for writing computer programs in Python. If you are a beginner in your software development journey, this Python cheat sheet can serve as a quick reference for all your Python queries.

#### Want a Top Software Development Job? Start Here!

Full Stack Development-MEAN ## Various Python Operators

Python operators are used to perform operations on variables and values. The main operators in Python are:

### Assignment Operators

Assignment operators assign values to variables.

=

x = 5

x = 5

+=

x += 3

x = x + 3

-=

x -= 3

x = x - 3

*=

x *= 3

x = x * 3

/=

x /= 3

x = x / 3

%=

x %= 3

x = x % 3

//=

x //= 3

x = x // 3

**=

x **= 3

x = x ** 3

&=

x &= 3

x = x & 3

|=

x |= 3

x = x | 3

^=

x ^= 3

x = x ^ 3

>>=

x >>= 3

x = x >> 3

<<=

x <<= 3

x = x << 3

### Arithmetic Operators

Arithmetic operators are used to perform common mathematical operations.

+

x + y

-

Subtraction

x - y

*

Multiplication

x * y

/

Division

x / y

%

Modulus

x % y

**

Exponentiation

x ** y

//

Floor division

x // y

#### Want a Top Software Development Job? Start Here!

Full Stack Development-MEAN ### Comparison Operators

Comparison operators are used to compare two values.

#### Example

==

Equal

x == y

!=

Not equal

x != y

>

Greater than

x > y

<

Less than

x < y

>=

Greater than or equal to

x >= y

<=

Less than or equal to

x <= y

### Logical Operators

Logical operators are used to combine conditional statements.

#### Example

and

Returns True if both statements are true

x < 5 and  x < 10

or

Returns True if one of the statements is true

x < 5 or x < 4

not

Reverse the result, returns False if the result is true

not(x < 5 and x < 10)

### Membership Operators

Membership operators are used to test if a sequence is presented in an object.

#### 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

#### Want a Top Software Development Job? Start Here!

Full Stack Development-MEAN ### Identity Operators

Identity operators are used to compare the objects to see if they are actually the same object with the same memory location.

#### Example

is

Returns True if both variables are the same object

x is y

is not

Returns True if both variables are not the same object

x is not y

### Bitwise Operators

Bitwise operators are used to compare binary numbers.

#### Description

AND

Sets each bit to 1 if both bits are 1

|

OR

Sets each bit to 1 if one of two bits is 1

^

XOR

Sets each bit to 1 if only one of two bits is 1

NOT

Inverts all the bits

<<

Zero fill left shift

Shift left by pushing zeros in from the right and let the leftmost bits fall off

>>

Signed right shift

Shift right by pushing copies of the leftmost bit in from the left, and let the rightmost bits fall off

## Data Types

In Python, every value is referred to as an object and every object has a specific data type. The three most used data types in Python are integers, floating-point numbers, and string.

### Integer (int)

An integer is used to represent an object such as “number 5”.

Example: -2, -1, 0, 1, 2, 3

### Floating-Point Number (float)

Float is used to represent floating-point numbers.

Example: -1.25, -1.0, – 0.5, 0.0, 0.5, 1.0, 1.25

### String

A string is used to modify a sequence of characters. For example, the word “hello”. Also, remember that strings are immutable in Python. This means that if you have already defined one, you cannot change it later on.

Example: ‘hello’, ‘bye’, hi’, ‘goodbye’

Other common data types in Python are lists, dictionaries, and tuples.

#### Want a Top Software Development Job? Start Here!

Full Stack Development-MEAN ## Variables

Variables are used to temporarily store data in the computer’s memory.

### Example:

price = 100

rating = 4.7

course_name = ‘Python for Beginners’

published = True

In the above example, price is an integer (a whole number with no decimal points), rating is a floating-point number (a number with a decimal point), course_name is a string (a sequence of characters), and published is a boolean.

Boolean values in Python can be True or False.

## Functions

Functions in Python are used to break up the code into small chunks. These chunks are easier to read and maintain. It is also easier to find bugs in a small chunk rather than going through the entire program. These chunks can also be reused.

### Example:

def greet_user(name):

print(f”Hi {name}”)

greet_user(“John”)

Parameters are the placeholders for data to pass through functions. Arguments are the values passed.

There are two types of values - positional arguments (their position matters) and keyword arguments (their position doesn’t matter).

### Positional Argument Example:

greet_user(“John”, “Smith”)

### Keyword Argument Example:

calculate_total(order=30, shipping=8, tax=0.1)

Functions can return values. If in case you don’t use the return statement, None is returned by default. None represents the absence of a value.

### Example:

def square(number):

return number * number

result = square(2)

print(result)

The above function will print 4 as a result.

## Flow Control

### Comparison Operators

Comparison operators are used to compare two values and evaluate True or False depending on the values you give them.

#### Meaning

==

Equal to

!=

Not equal to

<

Less than

>

Greater Than

<=

Less than or Equal to

>=

Greater than or Equal to

#### Example:  ### Boolean Evaluation

If you want to evaluate a boolean operation in Python, never use == or != operators.

Use the “is” or “is not” operators, or use implicit boolean evaluation.

#### Example:  ### Boolean Operators

There are three Boolean operators in Python - and, or, and not.

The “or” operator’s Truth Table:

#### Value

True or True

True

True or False

True

False or True

True

False or False

False

The “or not” operator’s Truth Table:

 Expression Evaluates to not True False not False True

The “and” operator’s Truth Table:

True and True

True

True and False

False

False and True

False

False and False

False

#### Example:   ### If-Else Statements

The if-else statement is used to execute both the true and false parts of a given condition. If the condition is true, the “if” block code is executed. If the condition is false, the “else” block code is executed. The elif keyword prompts your program to try another condition if the previous one is not true.

#### Example: ## Python Loops

Python has two loop commands that are good to know - for loops and while loops

### For Loop

The for loop is used to iterate over a sequence such as a list, string, tuple, etc.

#### Example: ### While Loop

The while loop enables you to execute a set of statements as long as the condition is true.

#### Example: ### Break and Continue

The break and continue statements are used to alter the loops even if the condition is met. It can be used in, both, for and while loops. ### Loop and Range Functions

If you want to loop through a set of code a number of times, you can use the range() function. It returns a sequence of numbers, starting by 0 from default, increments by 1 (default), and ends at a specified number. ## Exit and Sys.exit

The exit() and sys.exit() both have the same functionality as they raise the SystemExit exception where the Python interpreter exits and no stack traceback is printed. The main difference is that exit is a helper for the interactive shell and sys.exit is used in programs.

### Example: ## Return Values and Return Statements

A return statement is used at the end of the function call and returns the result or the value of the expression to the caller. Any statement after the return statements is not executed. In case the return statement does not have any expression, then “None” is returned.

## Keyword Print

The print() function in Python is used to print the specified message on the screen. This message can be a string or any other object. In case of an object, it will be converted into a string before being written to the screen.

### Syntax:

print(object(s), sep=separator, end=end, file=file, flush=flush)

### Example: ## Local and Global Scope

Whenever we create a variable in PYthon, it is only available inside the region in which it is created. This is called the scope of the variable.

### Local Scope

A variable created inside a function that can only be used in that function belongs to the local scope of that function.

#### Example: ### Global Scope

A variable created in the main body of the code is called a global variable. It belongs to the global scope and is available from within any scope, global and local.

#### Example: ## Exception Handling

Exceptions are errors that crash programs. In Python, we can handle exceptions using try and except statements.

### Example:  Simplilearn