Introduction
The Simplest High Level Programming Language is Python. Python is a scripting Language so it does not need any kind compile.There is generally two types major python version Python2 and Python3 but Python3 is latest and more usefull.There are lot of Python3 Version .I will recommend to install Python version-3.8.10.You also can test your python script in online by using Google Colab.
Python3 Installation
First go to Python version-3.8.10 official link and download the python installer as your system i.e. Windows,Mac etc 32bit or 64 bit etc.Open Command Prompt(Windows) or Terminal(Mac/Linux) and type python or python3 and enter will show python interpreter with version if no python showing then add python path from your system settings.Now you have created your python envirionment for further programming.
If you wish you don't want to install python in your machine then you may try Google Colab where you need to create a new account and create a google colab envirionment and there you can write your python file as well as run on it.
Hello World Program
The First Hello World Program is :
The Output look like:
You can run the program on Command Prompt/Terminal :
Or You can run the program by writing a file with extension .py
Or You can write or run on Google Colab
Python Variables
🔵There are many variable types in Python
- booleans(Which have values True, Flase)
- integers(Which have values 1,100,532 etc)
- floats(Which have values 3.1441,3.02,976.65 etc)
- strings(Which have values "this is a string", "love","a" etc)
To check a variable type just type 'type(variable)' in the interpreter.
we can change boolean to integer by wraping int()
>>> int(True)
1
>>> int(False)
0
>>>
Similarly we can change integer into boolean by wraping 'bol' and vice varsa by wraping 'int'
>>> bool(1)
True
>>> bool(0)
False
>>>type(True)
<class 'bool'>
>>>int(True)
0
>>>
Hash (#) symbol is using for comment i.e. the texts after # in a line ignore by python
>>> #Nothing will happened
>>>
Similarly we can change integer into float by wraping 'float', vice varsa by wraping 'int'
>>> float(10)
10.0
>>> float(32)
32.0
>>> type(32.0)
<class 'float'>
>>> int(65.89) #returning integer value only not approximate
65
>>>
Similarly we can change all variable type into 'string' type variable by wraping string and sometimes vicevarsa for correct data
>>> str(10)
"10"
>>> str(True)
"True"
>>> str(45.86)
"45.86"
>>> type('45.86')
<class 'str'>
>>> int('65.89')
65
>>> float('65.89')
65.89
>>> int("76gh") #It will show error as 76 as well as gh present
Traceback (most recent call last):
File "", line 1, in
ValueError: invalid literal for int() with base 10: '76gh'
>>>
Manipulation with string variables
>>>a="This is a string variable" #set a variable 'a' with a string value = "This is a string variable"
>>>type(a)
>>><class 'str'>
>>>a #printing value of a
>>>"This is a string variable"
>>>print(a) #another way to print the value of a
>>>"This is a string variable"
>>>len(a) #print length of string
>>>25
>>>#25 means 25 character including space
>>>#The first character 'T' of the string has index 0
>>>a[0]
>>>'T"
>>>The last character index is 25-1=24 as first index start from zero so last character index always be one less than total length of the string
>>>a[24]
>>>'e'
>>>a[2:4] #This will print character from index position 2(third character) to index position 4(third character)
>>>'is'
>>>a[0:24:2] #Skipping 2,4,6,8,10,12,14,16,18,20,22 characters
>>>'Ti sasrn aib'
Escape with \
'\n' creates new line, '\t' creates a tab, '\\' creates special character with '\'
>>>s = "This is a line.\nThis is a new line."
>>> print(a)
This is a line.
This is a new line.
>>> print("\tabc")
abc
>>> print("\'")
"'"
>>> print("\"")
>>> """
Addition of string by "+" and repeat string by "*"
>>>s = "Abc" + "def"
>>> print(s)
"Abcdef"
>>> print("abc" *3)
"abcabcabc"
String split with split() gives a list
>>> a = "The forest have lion,tiger,deer,cow etc animals"
>>> a.split(",")
['The forest have lion', 'tiger', 'deer', 'cow etc animals']
>>>
String join with join() gives a new string from list
>>> a = "The forest have lion,tiger,deer,cow etc animals"
>>> b = a.split(",")
>>> c = ",".join(b)
>>> c
>>> "The forest have lion,tiger,deer,cow etc animals"
More useful methods to manipulate strings
>>> test = "How are you?Do you have a boat?....If yes please use it."
>>> test.strip(".")
>>> 'How are you?Do you have a boat?....If yes please use it'
>>> test.capitalize()
>>> 'How are you?do you have a boat?....if yes please use it.'
>>> test.title()
>>> 'How Are You?Do You Have A Boat?....If Yes Please Use It.'
>>> test.upper()
>>> 'HOW ARE YOU?DO YOU HAVE A BOAT?....IF YES PLEASE USE IT.'
>>> test.lower()
>>> 'how are you?do you have a boat?....if yes please use it.'
>>> test.swapcase()
'hOW ARE YOU?dO YOU HAVE A BOAT?....iF YES PLEASE USE IT.'
>>> test.replace("boat", "cycle")
'How are you?Do you have a cycle?....If yes please use it.'
>>> setup = "a marmoset goes into a bar..."
>>> setup.replace("a", "famous", 100) #change upto 100th
>>> 'a famous marmoset goes into a famous bar...'
>>> setup.startswith("a")
>>> True
>>> setup.endswith("bar")
False
>>> setup.find("bar")
23
>>> setup.rfind("a")
24
>>> setup.count("a")
4
>>> setup.isalnum()
False
Exercise
Q1. Creates a simple Calculator. hint: take input by a=input("Please enter your value:")
Lists, Tuples, Dictionarirs, and Sets
Python Lists data
The list can be created by third bracket i.e. [] .The elements of a list can be any kind variables i.e integer, float,boolean,string even another list, tuples and set can be also an element of a list.The first item of a list indexed by zero and so on.
>>> empty_list = []
>>> week_days = ["Sunday","Monday","Tuesday","Wednusday","Thursday","Friday","Saturday"]
>>> type(week_days)
>>> <tclass 'list'>
>>> week_days[0]
>>> 'Sunday'
>>> len(week_days)
>>> 7
List of List
>>> empty_list = []
>>> week_days = ["Sunday","Monday","Tuesday","Wednusday","Thursday","Friday","Saturday"]
>>> rand_list = "abc-def-ghi-jkl".split("-")
>>> rand_list
>>> ['abc', 'def', 'ghi', 'jkl']
>>> new_list = [week_days,rand_list]
>>> new_list
>>> [['Sunday', 'Monday', 'Tuesday', 'Wednusday', 'Thursday', 'Friday', 'Saturday'], ['abc', 'def', 'ghi', 'jkl']]
>>> new_list[1]
>>> ['abc', 'def', 'ghi', 'jkl']
