Python Syntax Essentials: Your Guide to Writing Smarter Code
Basics of Python
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Python is a widely used general-purpose, high-level programming language. It was developed by Guido van Rossum in 1991 and further developed by the Python Software Foundation. Python is a programming language that lets you work quickly and integrate systems more efficiently. There are two major Python versions: Python 2 and Python 3. Both versions are quite different.
Running Basic Python Program
There are many ways to run Python programs. Look at the most widely used and common ways to run the Python program.
Python Hello World
The following program demonstrates the Print the Hello World ten times.
Program
def print_hello_world(count):
for i in range(count):
print("Hello, World! ({i + 1})")
def main():
times_to_print = 10
print("Printing 'Hello, World!' {times_to_print} times:n")
print_hello_world(times_to_print)
if __name__ == "__main__":
main()
The Python language also has an interactive shell. This shell is a command-line interface that allows you to execute the Python source code interactively. The Python shell supports functions, variables, and dynamically importing libraries. The Python shell includes built-in help functions for accessing documentation on various Python modules and functions.
Here is the step for running the Python interactive shell.
You can start the Python interpreter by typing python (or python3 on some systems) in the terminal or command prompt. We can run the Python commands interactively.
To exit, we must type the exit() or press Ctrl+D.
Indentation in Python
Indentation is a fundamental aspect of Python’s syntax and is crucial for defining the structure of your source code. Other programming languages use the braces or block of keywords. However, Python language has the indentation to achieve this. It is not just for the readability of the code. It affects the execution of the code.
The following program demonstrates the Indentation in Python.
Program
def greet(name):
if name:
print(f"Hello, {name}!")
else:
print("Hello, World!")
greet("Alice")
greet("")
x = 10
name = "Alice"
age = 30
height = 5.7
sum = 5 + 3
product = 4 * 7
is_equal = (5 == 5)
is_greater = (5 > 3)
and_result = (True and False)
or_result = (True or False)
print("Sum: {sum}, Product: {product}")
print("Is equal: {is_equal}, Is greater: {is_greater}")
print("Logical AND result: {and_result}, Logical OR result: {or_result}")
temperature = 30
if temperature > 25:
print("It's hot outside!")
elif temperature > 15:
print("The weather is pleasant.")
else:
print("It's cold outside!")
for i in range(5):
print(i)
count = 0
while count < 5:
print(count)
count += 1
def add(a, b):
return a + b
result = add(3, 5)
print("Addition result: {result}")
fruits = ["apple", "banana", "cherry"]
fruits.append("date")
print("Fruits: {fruits}")
student = {"name": "John", "age": 21}
student["age"] = 22
print("Student: {student}")
coordinates = (10.0, 20.0)
print("Coordinates: {coordinates}")
unique_numbers = {1, 2, 3, 4}
print("Unique numbers: {unique_numbers}")
Python variables are very important for writing Python programs efficiently. Unlike other programming languages, you don’t need to explicitly declare a variable’s type. The Python language dynamically determines the type of variable based on the value. For example, we create a variable “num” and initialize it with an integer value, so the num type is int. Then, we store the float value in ‘nu.’ It becomes a ‘str’ type. This is called dynamic typing, which means a variable’s data type can change during runtime.
Python Identifiers
Python identifiers identify various entities in a Python program, such as variables, functions, classes, modules and other objects. Identifiers are fundamental to writing source code, allowing you to reference and manipulate these entities. Here are the rules for defining the Python Identifiers:
An identifier can include letters (a-z, A-Z), digits (0-9), and underscores (_).
The first character of identifiers must be a letter or an underscore. It cannot be a digit
Identifiers are case-sensitive. For example, myVar, MyVar, and MYVAR are considered different identifiers.
Identifiers are not the same as Python’s reserved keywords (e.g., if, else, while, class, etc.).
The identifier cannot include special characters like @, #, –
The following program demonstrates the Python Identifiers.
Program
my_var = 10
variable1 = 20
_hiddenVar = 30
className = "Example"
def calculate_total(a, b):
return a + b
class MyClass:
def __init__(self, value):
self.value = value
def display_value(self):
print("The value is: {self.value}")
result = calculate_total(5, 15)
print("The result of the calculation is:", result)
my_instance_variable = MyClass(42)
my_instance_variable.display_value()
Output
The result of the calculation is: 20
The value is: 42
Python Keywords
Python keywords are reserved words that have special meaning in the programming language. We cannot use keywords as identifiers in Python (e.g., variable names and function names) because they are part of the language’s syntax. Below is the list of keywords in Python.
False
None
True
and
as
assert
break
class
continue
def
del
elif
else
except
finally
for
from
global
if
import
in
is
lambda
nonlocal
Not
or
pass
raise
return
try
while
With
yield
We can see all the Python keywords using the current version of Python using the source code.
import Keyword
print(keyword.kwlist)
Comments in Python
Comments annotate source code in Python, making it easier to understand and maintain. The Python interpreter does not execute comments; they are meant purely for human readers. Here’s the breakdown of how comments work in Python.
Python Single Line Comment
In Python, Comments are used to explain and annotate the source code. The Python interpreter does not execute them, so they don’t affect the program’s behavior. They don’t affect the behavior of the program. Single-line comments are the simplest type and are meant to occupy just one line.
The following program demonstrates Comment in Python.
Program
first_name = "Neeraj"
last_name = "Kumar"
# print full name
print(first_name, last_name)
Output
Neeraj Kumar
Python Multi-line Comment
Python does not have dedicated syntax for multi-line comments like other programming languages. However, you can achieve multi-line comments using two common approaches. To create a multi-line comment, we can use multiple single-line comments by prefixing each line with the # symbol. This is the most straightforward method and is often preferred for its clarity
The following program demonstrates the multi-line comment example.
Program
"""
This is a multi-line comment.
You can write as much as you need here.
The Python interpreter will ignore it.
"""
print("Hello, World!")
Multiple Line Statements
In Python, we can write multiple statements on a single line or split a long statement into multiple lines for better readability. We can separate multiple statements on the same line using a semicolon (;)). This feature makes the language more readable, so we have this feature and can break long statements in different ways.
Using Backslashes ()
In the Python language, We can break statements into multiple lines using the backslash()> It is a very useful method when you are working with strings or mathematical operations in the Python language.
The following program demonstrates the program.
Program
sentence = "This is a very long sentence that we want to "
"split over multiple lines for better readability."
print(sentence)
# For mathematical operations
total = 1 + 2 + 3 +
4 + 5 + 6 +
7 + 8 + 9
print(total)
Output
We want to split This long sentence over multiple lines for better readability.
45
Using Parentheses
We can split statements over multiple lines inside the parentheses without needing backslashes in the list, tuples, or function arguments.
We can also work with docstrings or multiline strings. We can use triple quotes (single “” or double “).
The following program demonstrates the Triple Quotes for Strings.
Program
text = """HeroVired Interactive Live and Self-Paced
Courses to help you enhance your programming.
Practice problems and learn with live and online
recorded classes with HeroVired courses. Offline Programs."""
print(text)
Output
HeroVired Interactive Live and Self-Paced
Courses to help you enhance your programming.
Practice problems and learn with live and online
recorded classes with HeroVired courses. Offline Programs.
In Python, Strings can be enclosed using single, double, or triple quotes. Triple quotes allow for the creation of multiline strings. Double quotes are used to enclose a string that contains a single quote.
The following program demonstrates the Quotation in Python.
Program
text1 = "He said, 'I learned Python from the HeroVired"
text2 =' He said," I have created a project using Python"'
print(text1)
print(text2)
Output
He said, 'I learned Python from the HeroVired
He said," I have created a project using Python."
Continuation of Statements in Python
In Python, when a statement spans multiple lines, you need a way to indicate that the statement continues on the next line. There are several methods for this.
Implicit Continuation
Python language implicitly supports line continuation within parentheses (), square brackets [], and curly braces{}. This is often used in defining multi-line lists, tuples, and dictionaries of function arguments.
The following program demonstrates the implicit continuation.
Hero Vired is a computer science portal that HeroVired uses.
Strings
Strings in Python can span multiple lines using triple quotes (‘’’ or “). Furthermore, if two string literals are placed next to each other, Python will automatically concatenate them.
The following program demonstrates the Strings.
Program
text = ''' A Hero can help other
Geek by writing an article on Hero'''
message = "Hello, " "Vired!"
print(text)
print(message)
Output
A Hero can help other
Geek by writing an article on Hero
Hello, Vired!
Strings Literals in Python
String literals in Python are sequences of characters designed to represent textual data. They can be enclosed in single quotes (‘), double quotes (“), or triple quotes (‘’’ or “””). Each type of quoting method serves different purposes and offers flexibility in how text is represented and manipulated in the Python language.
The following program demonstrates the String Literals in Python.
Program
string1 = "Hello, Hero Vired"
string2 =" Namaste Hero"
multi_line_string = '''
Ram learned Python by reading a tutorial on HeroVired
'''
print(string1)
print(string2)
print(multi_line_string)
Output
Hello, Hero Vired
Namaste Hero
Ram learned Python by reading a tutorial on HeroVired
Command Line Arguments
In Python, the command line arguments allow you to pass input to a script when executing it from the command line. This argument follows the script’s name and can be accessed within the script.
The following program demonstrates the Command Line Arguments.
Program
import sys
if len(sys.argv) < 2:
print("Please provide numbers as arguments to sum.")
sys.exit(1)
try:
total = sum(map(float, sys.argv[1:]))
print(f"Sum: {total}")
except ValueError:
print("All arguments must be valid numbers.")<strong> </strong>
Output
Please provide numbers as arguments to sum.
Taking Input from User in Python
The ‘input()’ function in Python is used to get input from the user via the console. The function is called the program pauses and waits for the user to type in their input and press “Enter”. The function then returns the input data as a string. We can provide a prompt as an argument to the function to give the user instructions on what to enter.
The following program demonstrates the input function Python.
Program
def get_name():
"""Prompt the user to enter their name and return it."""
return input("Please enter your name: ").strip()
def get_age():
"""Prompt the user to enter their age, validate the input, and return it."""
while True:
try:
age = int(input("Please enter your age: ").strip())
if age < 0:
raise ValueError("Age cannot be negative.")
return age
except ValueError as e:
print("Invalid input: {e}. Please enter a valid age.")
def get_programming_experience():
"""Prompt the user to enter whether they have programming experience and return it."""
while True:
experience = input("Do you have any programming experience? (yes/no): ").strip().lower()
if experience in ['yes', 'no']:
return experience
else:
print("Invalid input. Please enter 'yes' or 'no'.")
def main():
"""Main function to interact with the user and provide feedback based on their input."""
name = get_name()
age = get_age()
experience = get_programming_experience()
print("n--- User Profile ---")
print("Name: {name}")
print("Age: {age}")
print("Programming Experience: {'Yes' if experience == 'yes' else 'No'}")
if experience == 'yes':
print("That's great! Keep up the good work with programming.")
else:
print("No worries! There are plenty of resources to help you get started with programming.")
if __name__ == "__main__":
main()
Output
Please enter your name: Neeraj
Please enter your age: 23
Do you have any programming experience? (yes/no): yes
--- User Profile ---
Name: {name}
Age: {age}
Programming Experience: {'Yes' if experience == 'yes' else 'No'}
That's great! Keep up the good work with programming.
Conclusion
This article taught us about the Python syntax essentials, which are crucial for writing effective and efficient source code. Understanding fundamental elements such as variable assignments, control flow statements, functions, and data structures creates clear, maintainable, and robust programs. Embracing these essentials empowers you to solve problems more intuitively and innovate confidently in your programming endeavors.
FAQs
How do I make a string in Python?
You create a string by enclosing text in single quotes (‘...’) or double quotes (“...”). For example
string1 = 'Hello'
string2 = "World"
How do I create a list in Python?
Lists are created using square brackets ([]) and can include multiple items separated by commas. For example
my_list =[1,2,3,4,5]
How do I loop through a list in Python?
We can use a for loop to iterate over the items in a list. For example
for item in my_list: print(item)
How do I define a simple function in Python?
The function name and parentheses use the def keyword, followed by a colon. for example
def greet(): print("Hello!")
How do I concatenate strings in Python?
Use the + operator to join strings together. For example
full_name = “Neeraj” + “ ”+ “Doe”
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