gs.mdx

title	sidebar_label
Python Basics	Get started

import Tabs from '@theme/Tabs'; import TabItem from '@theme/TabItem';

Python is a dynamically typed, interpreted language. Python interpreter is written in C-language. Interpreter program reads and performs the Python codes/ instructions. The interpreters interacts with the operating system layer (use network, keyboard, mouse, monitor, hard drive etc.).

Hello Python

It is customary to write our first program that prints some message in the screen: <Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

print("Hello Python!")

Hello Python!

Assigning variables

<Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

a = 5
b = 3
a + b

8

<Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

a * b

15

<Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

a - b

2

:::tip Good to know

Due to how the numbers are stored in computer memory, floating point algebra sometimes might produce unexpected results. Notice the following discrepancy (floating point addition/ subtraction is not associative):

>>> (1.2 + 1E20) - 1E20
0.0
>>> 1.2 + (1E20 - 1E20)
1.2

:::

String concatenation

<Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

greeting = "Hello"
name = "Pranab"
print(greeting + " " + name)

Hello Pranab

For performance improvement and better readability, consider using join instead of in-place string concatenation.

" ".join([greeting, name])

Loosely typed

As we have seen, we do not need to define the datatype in python. Interestingly, for certain operations, we can even mix types: <Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

my_str = "Rain! "
my_str * 3  # multiplying a str with int

'Rain! Rain! Rain! '

Input

Collecting user input: <Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

age = input("How old are you? ")
type(age)

How old are you? 34
<class 'str'>

:::note Notice that variable assigned from input is a string, even if a number is entered. :::

Type conversion

<Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

age = int(age)
type(age)

<class 'int'>

String formatting

<Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

"Singapore".upper()

'SINGAPORE'

<Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

"Singapore".lower()

'singapore'

<Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

"das".capitalize()

'Das'

<Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

"pranab das".title()

'Pranab Das'

<Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

"ABCDefgh".swapcase()

'abcdEFGH'

<Tabs defaultValue="input" values={[ { label: 'Input', value: 'input', }, { label: 'Output', value: 'output', }, ] }>

name = 'Pranab'
age = 34
print("Name: {0}. Age: {1} years.".format(name, age))

Name: Pranab. Age: 34 years.

You can also format in the following way:

print("Name: {name}. Age: {age} years.".format(name=name, age=age))

Starting from Python 3.6 and above:

print(f"Name: {name}. Age: {age} years.")