Chapter 1 Fundamentals of python programming

CHAPTER1: FUNDAMENTALS OF PYTHON PROGRAMMING

Programming is a way of giving instructions to a computer system or a machine in order to operate it.
With the use of programming , many kinds of software can be developed.
A person who develops software with the help of programming is called a software engineer or a software developer.
The process of giving instructions to a machine is also a type of communication.
As in a normal communication,to communicate through a machine or a computer,a language is also required.This language is called programming language.
The programming languages are also of different types.These are also called computer languages.They are basically of three types:-

Machine language or binary language
Assembly level language
High-level language

Machine language and assembly language are not much important to know according to this course.
High-level programming language is a language that uses english like words and mathematical operation.

Python is a high level programming language ,with applications in many areas.
It is used in web programming ,scripting ,scientific computing,machine learning ,artificial intelligence and in education.

The very basic instruction that can be given to a computer is to print something on the output screen.
In python,print function is used to accomplish this task.
SYNTAX :- print()
The program with the help of print function will be discussed later.
Python has the ability to perform calculations.It's mathematical syntaxes are very much similar to mathematics.Some of the python operations are as under:-

Operator	Operation	Example
"+"	Addition	2+2= 4
"-"	Subtraction	5-2= 3
"*"	Multiplication	3*3= 9
"/"	Decimal division	3/2 = 1.5
"//"	Integer division	3//2 = 1
"**"	Exponentiation	25**2 = 625
"%"	Modulo division	9%4 = 1

Addition : It is used to add numbers.
Subtraction : It is used to find difference between numbers
Multiplication : It is used to find the product of numbers.
Decimal division : It is used to produce a decimal point number by operating it on numbers.
Integer division : It is used to obtain integer from division without considering the remainder.
Exponentiation : It used to find the power of a number.
Modulo division : It is used to find the remainder after the occurence of operation.

DATA TYPES IN PYTHON PROGRAMMING LANGAGE

In programming , data types are very important. Due to them ,the complexity in a program is reduced.In python following are the major data types :-

Strings : These are collection of characters inside single quotation marks(') and double quotation(") marks.Any text in python programming language has a data type called a string.
Ex :- print("Ayush Sinha")

>>>
Ayush Sinha
>>>
Integers : These are simply called numbers without a decimal or floating point.
Ex : 3,67,45,-234,-6,78,-89,34,etc
Floats : These are decimal point numbers.
Ex: 2.67,5.6789,-56.88997,-2.56,3.0,6.0,etc
Boolean : It refers to the value which may be either true or false.In other words, It represents two values : True and False.
Lists : These are data structure used to store an indexed collection of items. Ex :- [ "Ayush",3,56.89,True]
The above list stores a collection of various data types.It contains a string,an integer,a float,and a boolean value.They can store any type of data.They are created using square [] brackets.
Tuple : These are very similar to the lists except that they are immutable.It means they can't be changed if once created.They can also store any type of data.They are created using paranthesis () .
Ex: ( "Ayush",3,56.89,True)
Dictionaries : Dictionaries are data structure used to store complex form of data.They are created using curly braces {} and used to store data in the form of a key:value pair.
Ex : {
1: "Ayush",
2:"Rohit",
3:"Rahul",
}

Exercise 1.0

Q1. What is the data type of "Ayush4444" ?
Q2.Evalute: (((4/2)//2)**2)**2)+100
Q3. What will be the output of this code? ----------> print('print('print('print(0)')')')

Variables and Constants

The concept of variables and constants in programming is very much similar to the concept in mathematics.But in programming ,the numbers are replaced by the data and information.Thus,In programming we work with data and information. Variables and constants are an essential part of programming.
Variable: A variable is like a placeholder that is used to store a piece of information.Its value(information) can be changed in a program.
Constant :Any information is called constant.It may be in many forms or types and are categorised as data types. To understand the concept of variables and constants ,following program can be seen:-

x = 25
y = 35
z = "third variable"
x = z
z2 = y
z3 = y
print(x)
print(y,z)
print(z,z2,z3)

The output of above code will be :-

>>>
third variable
35 third variable
third variable 35 35
>>>

Strings

In programming,the concept of strings is very important.In python programming language,the string data type has many concepts withit which needs to be understand.
Now,There are some concepts related to strings which needs to be discussed:-

String Concatenation :

String concatenation is a process of adding strings.The process is not much similar to the addition of numbers(integers or floats).In this process ,one string is appended to the last of string.Strings cannot be added with an integer or float.However it can be added to "5" because it is a string.For example if add two strings containing numbers such as "5" and "3" then the result will be "53" .Because concatenating two strings only means to append one string to the end of other string.There is no logical calculation while performing string concatenation.To add the above string contaning numbers,mathematically,int function can be used.They can be added like int("5") + int("3"), then the result will be 8.Please note that the resultant 8 has not have any quotation marks.Because it is a number and the result of addition of two integer is an integer not a string.Similarly to convert any data type into a string,str function can be used.Following is an example of string concatenation:-

x = "Ayush"
y = "Sinha"
z = x + y
print(z)

The output of above code will be Ayush Sinha

String Slicing

String slicing or selecting subsequences from strings is a process of extracting substring from the string.To accomplish it,indexing of string should be performed first.
In python,the each and every character has a special position.This is called the index of the character in that string.
Ex: "Python" ,here index of "P" is 0.Remember ,the first index of each and every string in python begins with 0 and moves on as 1,2,3,4.... so on.
The concept of string slicing is as under:-

name = "Ayush"
subname = name[3]
print(subname)
output---------->>>>> s
name = "Ayush"
subname = name[0:3]
print(subname)
output---------->>>>> Ayu
name = "Ayush"
subname = name[0:]
print(subname)
output---------->>>>> Ayush
name = "Ayush"
subname = name[0:]
print(subname)
output---------->>>>> Ayush
name = "Ayush"
subname = name[0:]
print(subname)
output---------->>>>> Ayush
name = "Ayush"
subname = name[0:]
print(subname)
output---------->>>>> Ayush
name = "Ayush"
subname = name[:]
print(subname)
output---------->>>>> Ayush
name = "Ayush"
subname = name[:4]
print(subname)
output---------->>>>> Ayus
name = "Ayush"
subname = name[-1]
print(subname)
output---------->>>>> h
name = "Ayush"
subname = name[-3]
print(subname)
output---------->>>>> u
name = "Ayush"
subname = name[0:5:1]
print(subname)
output---------->>>>> Ayush
name = "Ayush"
subname = name[0:5:2]
print(subname)
output---------->>>>> Auh
name = "Ayush"
subname = name[-1::-1]
print(subname)
output---------->>>>> hsuyA
name = "Ayush"
subname = name[::-1]
print(subname)
output---------->>>>> hsuyA

String Formatting

String formatting is a way to format your strings with other data types.It used when strings have to be displayed with other data types such as integers,floats and other data structure.It provides comfort to the programmers to display strings with other data types without involving the type conversion.Type conversion is a process of turning one data type to another data type.It will be discussed later in the course.Following is an example of string formatting.

name = "Ayush Sinha"
age = 25
print(f "The name is {name} and age is {age}")

The output of above code will be:-

>>>
The name is Ayush Sinha and age is 25
>>>

Getting User Input

To get the input of user is very important in console based programming.In python,to get user input, input function is used.One important thing about input function is that, it always takes data as input in the form of strings. The input taken by the user can be stored in a variable and from there it can be used in the program.The syntax of input function is as under:-

name = input("Enter your name : ")
age = input("Enter your age : ")
print(f "Hello {name}, your age is {age}")

The output of above code will be:-

>>>
Enter your name : Ayush Sinha
Enter your age : 25
Hello Ayush Sinha,your age is 25
>>>

Exercise 1.1

Q1.Write a program that will take two numbers from the user and will give the sum.
Q2. Write a program that will take the name of user as an input and will give his/her name in reverse order.
Q3.Write a program that will take a number from the user and will display the square and cube of that number.
Q4.Write a program that will take a number from the user and will return the squre root and cube root of that number.
Q5.Write a program that will take a number as an input from the user and will return the assigning number.(ex:-Assigning number of 1356 => 35/16 = 2.1875)
Q6.Write a program that will take a word from the user and convert it in cyper languge(ex:-cyper language of the word 'player' is 'lyerpa' and cyper language of the word 'action' is 'cionat')

Methods used with Strings

Many functions can be performed with strings.These functions can be accomplished by using string methods. These methods are as under:-

Len function:- It used to find the length of a given string.
syntax:- len(string_name)
Find Method:- It is used to find the index of a certain character in a string.
syntax:- string_name.find(parameter)
Upper Method:- It is used to convert all the string characters in the upper case.
Syntax:- string_name.upper()
Lower Method:- It is used to convert all the string characters in the lower case.
Syntax:- string_name.lower()
Count method:- It is used to count the number of particular character in a string.
syntax:- string_name.count(char)
Title Method:- It is used to convert the first string character in the upper case.
Syntax:- string_name.title()
Split Method:- It is used to split the string by the parameter passed in the method.
Syntax:- string_name.split()
Strip Method:- It is used to eradicate the spaces in the string.
Syntax:- string_name.strip()
Replace Method:- It is used to replace a character or a substring with a other string or character.
Syntax:- string_name.replace()

string_name= 'Ayush Sinha'
x = len(string_name)
y = string_name.find(h)
z = string_name.find(h,y+1)
upper = string_name.upper()
lower= string_name.lower()
char_count= string_name.count(h)
splitted_string = string_name.split(",")
titled_string = string_name.title()
new_string= " Ayush "
strip_string = new_string.strip()
splitted_string = string_name.replace("sinha","malhotra")

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