How to Use Python: A Beginner’s Guide 

Python is a high-level object-oriented programming language that is causing quite a stir in the programming world. Python is used in every IT field, from software development to data mining, to generate practical applications and services.

Did you know that Python is one of the most popular programming languages in the world? With so many advantages, it’s ideal for aspiring programmers to try their hand with Python.

Have you made the decision to learn Python? Then let’s dig into an in-depth look at how to set up and use Python:

How to Install Python?

Because Python is not preinstalled with Windows, we will most likely need to install it ourselves.

Let’s get started with our complete guide by looking at the detailed steps for installing Python on a desktop computer.

Step 1: Choose a Python Version to Install

First, the Python.exe installer should be installed in your system.

Visit the official website and select the most recent version that is compatible with your computer’s operating system and begin the download process.

Step 2: Download Python Executable Installer

Open your web browser and go to the official Python website’s Downloads for Windows or Mac section.

Look for the Python version you require. The average download size is under 25MB, so you may download the software in minutes.

Step 3: Run Executable Installer

  • Run the Python Installer after the installation is complete.
  • Ensure that the checkboxes for Install launcher for all users and Add Python version to PATH are both checked. The interpreter is then placed on the execution path.
  • Select Install Now and follow the on-screen instructions to complete the installation.
  • The following dialogue will ask you whether you want to disable the path length limit. By selecting this option, Python will be able to get around the 260-character MAX PATH limit, and it will effectively allow Python to use prominent path names.
  • The Disable path length limit option will be unaffected by any other system settings. By enabling it, problematic name length issues with Python programmes written on Linux will be resolved.

Step 4: Double-Check That Python Is Installed on Windows

Following the installation, the following step is to determine whether Python is installed on the machine. To determine that,

  • Head to the Python installation location on your computer.
  • Double-click Python.exe to launch it.

Here you will be able to check whether Python was installed on your PC or not.

Step 5: Install Virtualenv

After Python is installed along with Pip which is used to manage packages. The next step would be installing another tool. 

Along with Pip, there is another essential software called virtualenv. 

Virtualenv allows you to construct isolated local virtual environments for your Python projects.

What Exactly Is Virtualenv?

virtualenv is a utility for establishing isolated Python environments, each with its own copy of Python, pip, and a location to store libraries downloaded from PyPI. It’s made to let you work on several projects with various dependencies on the same machine simultaneously.

To set up virtualenv, follow these steps.

  • Type “cmd” into the Start menu.
  • Choose the Command Prompt program.
  • In the console, type the following pip command:
Username> pip install virtualenv

How to Call a Function in Python?

A function in Python is a reusable chunk of code that is used to accomplish a single, related operation. Functions provide your program with more modularity and allow you to reuse a lot of code.

As you may be aware, Python includes a number of built-in functions, such as print(), but you may also construct your own. User-defined functions are what they’re called.

Defining a Function

You can create functions to deliver the functionality you need. Before defining a function in Python, follow these simple guidelines.

  • The term def is followed by the function name and parenthesis in a function block.
  • Within the parenthesis, any input parameters or arguments should be entered.
  • The function’s documentation string, or docstring, might be an optional statement in the initial statement of a function.
  • Every code block in a function starts with a colon (:) that is perfectly indented.
  • The return [expression] statement exits a function and returns an expression to the caller if it is specified. Return None is the same as a no-argument return statement.

Syntax:

def functionname( parameters ):
"function_docstring"
   function_suite
  return [expression]

Calling a Function

Giving a function a name, describing the arguments that must be included in the function, and arranging the code blocks are all part of the definition process.

Once the core structure of a function is ready, you may run it by calling it from another function or directly from the Python prompt.

Pass by reference vs. value

All parameters (arguments) are supplied by reference in the Python programming language. It means that if you modify the value of a parameter within a function, the change is also reflected in the calling function.

Example:

def evenOdd(x):
    if (x % 2 == 0):
        print("even")
    else:
        print("odd")
#function calling
evenOdd(2)
evenOdd(3)

Output:

even

odd

How to End a Program in Python?

When we execute a Python program, we simply run all of the code in the file from top to bottom. Scripts generally exit when the interpreter reaches the end of the file, but we can use the built-in exit routines to force the program to exit.

The routines quit(), exit(), sys.exit(), and os. exit() all raise the SystemExit exception, which causes the Python interpreter to exit without printing a stack traceback:

quit()

quit() only works if you import the site module; hence it shouldn’t be used in production code. The term “production code” refers to code that is being utilized in a real-world setting by the target audience. Only the interpreter should use this function.

exit()

exit() should only be used in the interpreter because exit() is defined in site.py and only functions if the site module is imported. To make Python more user-friendly, it acts as a synonym for quit().

sys.exit([arg])

Because the sys module is always available, unlike quit() and exit(), sys, exit() is deemed suitable to use in production programs. Depending on the case, the optional argument arg can be an integer or another type of object. Zero is termed “successful termination” if it is an integer.

os._exit(n)

In Python, the os. exit() method is used to exit a process with a defined status without having to run cleanup handlers, flush stdio buffers, and so on.

How to Comment in Python?

In Python, comments are lines of code that are disregarded by the compiler during the program’s execution. Comments improve the readability of the code and assist programmers in completely comprehending it

In Python, there are three sorts of comments:

  • Single line Comments
  • Multiline Comments
  • Docstring Comments

Single-Line Comments

A single-line comment in Python begins with the hashtag symbol (#) and continues to the end of the line. If the comment is longer than one line, add a hashtag to the following line and continue the conversation. 

Single-line comments in Python have effectively provided quick explanations for variables, function declarations, and expressions. 

Multi-Line Comments

Multiple-line comments aren’t available in Python. However, there are a variety of methods for writing multiline comments.

Using Multiple Hashtags (#)

We can use several hashtags (#) to construct multiline comments in Python. Every single line will be treated as a single-line remark.

Docstring Comments

The literal strings with triple quotes come right after the function. It’s used to link documentation written for Python modules, functions, classes, and methods together. It’s placed just beneath the functions, modules, and classes to explain what they perform. The docstring is made available in Python using the __doc__ attribute.

Comments are generally used for the following purposes: 

  • To enhance the code readability
  • To provide a clear explanation of the code or Metadata of the project
  • Prevent execution of specific unnecessary codes.
  • To include resources that may be useful for later.

How to Loop in Python?

Statements are usually executed in the following order: 

  • The first statement in a function is executed first, then the second, and the process repeats. 

Sometimes there might be instances where you will need to execute a certain block of code multiple times and this is satisfied using loops.

A loop statement allows us to repeat the execution of a statement or a series of statements. A loop statement is depicted in the diagram below.

To meet looping requirements, the Python programming language supports the following types of loops to meet looping requirements.

Loop Control Statements

Control statements in loops change the order of execution. Once the execution leaves that scope, all of the automated objects created in that scope are removed.

Python supports the following control statements. 

For loop

It repeats a sentence or combination of phrases while a defined condition is TRUE. The for loop examines the condition before performing the loop body.

Syntax:

for val in sequence:
    #loop body

The variable val here is used to store the value of each item in the sequence on each iteration.

Example:

nums = (1, 2, 3, 4)
sum_nums = 0
for num in nums:
    sum_nums = sum_nums + num
print('Sum of numbers is {sum_nums}')

Output:

Sum of numbers is 10

While loop

The code that maintains the loop variable is condensed and executes a sequence of statements many times.

Syntax:

while test_expression:
    #Body of while

The test expression is checked initially in the while loop. The body of the loop is entered if the test expression evaluates to True. After one cycle, the test expression is verified again, and the process is continued until the test expression returns False.

Example:

n = 10
# initialize sum and counter
sum = 0
i = 1
while i <= n:
    sum = sum + i
    i = i+1    # update counter
# print the sum
print("The sum is", sum)

Output:

The sum is 55

Nested loop

You can use one or more loops inside any another while, for, or do..while loop.

Syntax:

for iterating_var in sequence:
   for iterating_var in sequence:
      statements(s)
   statements(s)

Example:

words= ["Avocado", "Banana", "Lorry", "Whale" ]
for a word in words:
        print ("The following lines will print each letters of "+word)
        for letter in word:
                print (letter)
        print("") 

Output:

The following lines will print each letter of Avocado

A
v
o
c
a
d
o

The following lines will print each letter of Banana

B
a
n
a
n
a

The following lines will print each letters of Lorry

L
o
r
r
y

The following lines will print each letters of Whale

W
h
a
l
e

Let us go through the loop control statements briefly.

  • break Statement

The loop statement is terminated, and execution is transferred to the statement immediately following the loop.

  • continue Statement

The continue statement causes the loop to skip the rest of its body and retest its condition before repeating.

  • pass Statement

When a statement is required syntactically, but no command or code is to be executed, the pass statement is used in Python.

How to Reverse A String in Python?

Manipulating strings is probably one of the best ways to try out various features provided by a programming language. If you are looking to reverse a string in Python, then you should understand that there is no direct built-in function to do so.

However, you can use a reverse slice method to do so!

Example:

txt = "Python is fun" [::-1]
print(txt)

Output: 

nuf si nohtyP

How to Round in Python?

You can round any number in Python using the built-in round() function. 

Syntax:

round(number, digits)

Where, 

Number is the required input parameter that needs to be rounded.

Digits indicate the number of decimals to be used while rounding the number. If this parameter isn’t mentioned, the default will be considered zero.   

Example 1:

x = round(88.96712, 2)
print(x)

Output: 

88.97

Example 2:

x = round(88.96712)
print(x)

Output: 

89

Advantages and Disadvantages of Python

Like every other programming language, Python has its own set of benefits and drawbacks. Here are a few that every developer should be aware of:

Advantages:

  • Open-Source and Free Software
  • Simple to Understand.
  • Provides vast support for an extensive standard library
  • Because it is an interpreted language, the possibility of errors is low.
  • Dynamically Typed

Disadvantages: 

  • Poor Memory Capacity
  • Execution time is slow.
  • The database access layer is still in its development.
  • It’s not possible to use it in front-end development.
  • Errors that occur during execution.

Conclusion

Python is now employed in practically every IT industry, and the widely utilized programming language is used to develop cutting-edge software and applications. 

We hope you learned how to install Python and perform basic tasks with it. It’s always a great idea to try out as many built-in functions as you can and get practical learning exposure.

If what you’ve just read is all new to you, why not dip your toe in the water of code? Try our free 5 Day Coding Challenge and learn the basics of HTMLCSS and JavaScript. Register now through the form below. On the other hand, if you want to become a full-stack Python developer, then read more about our Full-Stack programme.

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