Python Programming Advance 2022

Visit the link https://www.python.org/downloads/ to download the latest release of Python. In this process, we will install Python 3.6.7 on our Windows operating system.

Double-click the executable file which is downloaded, select customize installation and proceed.

The following window shows all the optional features. All the features need to be installed and are checked by default, we need to click next to continue.

The following window shows a list of advanced options. Check all the options which you want to install and click next. Here, we must notice that the first check-box (install for all users) must be checked.

Now we are ready to install python-3.6.7 Lets install it.

Now try to run python on the command prompt. Type the command python in case of python2 or python3 in case of pyton3. It will show an error as given in the below image. It is because we haven’t set the path.

To set the path of python, we need to right click on “My Computer” and go to properties è Advance è Environment Variables.

Add the new path variable in the user variable section.

Type PATH as the variable name and set the path to the installation directory of the python shown in the below image.

Now, the path is set, we are ready to run python on our local system. Restart CMD and type python again. It will open the python interpreter shell where we can execute the python statements.

Python Variables

Variable is a name which is used to refer memory location. Variable also know as identifier and used to hold value. In Python, we don’t need to specify the type of variable because Python is a type infer language and smart enough to get variable type.

Variables names can be a group of both letters and digits, but they have to begin with a letter or an underscore.

It is recommended to use lowercase letters for variable name. Rahul and rahul both are two different variables.

Identifier Naming

Variables are the example of identifiers. An Identifier is used to identify the literals used in the program. The rules to name an identifier are given below.

· The first character of the variable must be an alphabet or underscore ( _ ).

· All the characters except the first character may be an alphabet of lower-case(a-z), upper-case(A-Z), underscore or digit (0-9).

· Identifier name must not contain any white-space, or special characters (!, @, #, %, ^, &, *)

· Identifier name must not be similar to any keyword defined in the language.

· Identifier names are case sensitive for example my name and MyName is not the same.

· Example of valid identifiers: a123 or _n or n_9 etc.

· Examples of invalid identifiers: 1a, n%4,n 9 etc

Declaring Variable and Assigning Values

Python does not bound us to declare variable before using in the application. It allows us to create variable at required time. We don’t need to declare explicitly variable in Python. When we assign any value to the variable that variable is declared automatically.

The equal ( - ) operator is used to assign value to a variable.

Python Literals

Literals can be defined as a data that is given in a variable or constant.

Python supports

1. String literals

         a. Adding back slash at the end of each line

         b. Using triple quotation marks.

2. Numeric Literals

3. Boolean Literals

4. Special Literals

5. Literal Collections

Python Operators

The operator can be defined as a symbol which is responsible for a particular operation between two operands. Operators are the pillars of a program on which the logic is built in a particular programming language. Python provides a variety of operators described as follows.

o Arithmetic operators

o Comparison operators

o Assignment operators

o Logical operators

o Bitwise operators

o Membership operators

o Identity operators

Python supports the usual logical conditions from mathematics:

• Equals: a == b

• Not Equals: a != b

• Less than: a < b

• Less than or equal to: a <= b

• Greater than: a > b

• Greater than or equal to: a >= b

These conditions can be used in several ways, most commonly in "if statements" and loops.

An "if statement" is written by using the if keyword.

Example 1: (If statement)

a = 33

b = 200

if b > a:

print("b is greater than a")

Output:

b is greater than a

Why we use loops in python?

The looping simplifies the complex problems into the easy ones. It enables us to alter the flow of the program so that instead of writing the same code again and again, we can repeat the same code for a finite number of times. For example, if we need to print the first 10 natural numbers then, instead of using the print statement 10 times, we can print inside a loop which runs up to 10 iterations.

Advantages of loops

The following advantages of loops in Python.

1. It provides code re-usability.

2. Using loops, we do not need to write the same code again and again.

3. Using loops, we can traverse over the elements of data structures (array or linked lists).

The python while loop allows a part of the code to be executed until the given condition returns false. It is also known as a pre-tested loop.

It can be viewed as a repeating if statement. When we don’t know the number of iterations then the while loop is most effective to use.

The syntax is:

While expression:

Statements

Here, the statements can be a single statement or a group of statements. The expression should be any valid python expression resulting in true or false. The true is any non-zero value and false is 0.

The break is a keyword in python which is used to bring the program control out of the loop. The break statement breaks the loops one by one, i.e., in the case of nested loops, it breaks the inner loop first and then proceeds to outer loops. In other words, we can say that break is used to abort the current execution of the program and the control goes to the next line after the loop.

The break is commonly used in the cases where we need to break the loop for a given condition.

The syntax of the break is:

#loop statements

Break;

Example:

list =[1,2,3,4]

count = 1;

for i in list:

if i == 4:

print("item matched")

count = count + 1;

break

print("found at",count,"location");

Example 2

str = "python"

for i in str:

if i == 'o':

break

print(i);

The continue statement in Python is used to bring the program control to the beginning of the loop. The continue statement skips the remaining lines of code inside the loop and start with the next iteration. It is mainly used for a particular condition inside the loop so that we can skip some specific code for a particular condition. The continue statement in python is used to bring the program control to the beginning of the loop. The continue statement skips the remaining lines of code inside the loop and start with the next iteration. It is mainly used for a particular condition inside the loop so that we can skip some specific code for a particular condition.

Syntax for continue statement

# loop statements

Continue

# the code to be skipped