Basics to start with in python

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Python Basics

Python Basics

Hello World


print("Hello, World!")
Output:
Hello, World!

Variables and Data Types


num = 42
pi = 3.14
name = "Alice"
is_student = True

Playing with Strings


# Define a sample string
sample_string = "Hello, World!"

# Indexing: Accessing characters by index
print("Indexing:")
print("Character at index 0:", sample_string[0])  # Output: H
print("Character at index 7:", sample_string[7])  # Output: W

# Slicing: Extracting substrings
print("\nSlicing:")
print("Substring [0:5]:", sample_string[0:5])  # Output: Hello
print("Substring [7:]:", sample_string[7:])    # Output: World!
print("Substring [:5]:", sample_string[:5])    # Output: Hello

# Reverse the string
print("\nReversed:")
reversed_string = sample_string[::-1]
print("Reversed string:", reversed_string)     # Output: !dlroW ,olleH

# Length of the string
print("\nLength:")
print("Length of the string:", len(sample_string))  # Output: 13

# Uppercase and lowercase letters
print("\nUppercase and Lowercase:")
print("Uppercase:", sample_string.upper())   # Output: HELLO, WORLD!
print("Lowercase:", sample_string.lower())   # Output: hello, world!

# Split the string into a list of words
print("\nSplit:")
split_words = sample_string.split(', ')
print("Split words:", split_words)          # Output: ['Hello', 'World!']

# Looping through the string
print("\nLooping:")
print("Characters in the string:")
for char in sample_string:
    print(char, end=' ')  # Output: H e l l o ,   W o r l d !

Loops

Using loops to iterate through a range and a while loop.


for i in range(5):
    print(i)

num = 1
while num <= 5:
    print(num)
    num += 1
Output:
For loop Output 0 1 2 3 4
While loop output 1 2 3 4 5

Functions

Defining and calling functions.


def greet(name):
    print("Hello,", name)

greet("Alice")

def add(a, b):
    return a + b

result = add(5, 6)
print("Sum:", result)
Output:
The output for the above three functions are as follows
Hello,
Alice
Sum: 11

Lists

Working with lists and loop through elements.


numbers = [1, 2, 3, 4, 5]
names = ["Alice", "Bob", "Charlie"]
mixed = [1, "Alice", True]

# Append to a list
numbers.append(6)

# Loop through a list
for num in numbers:
    print(num)
Output:
1 2 3 4 5 6

Tuples

Working with tuples and unpacking.


# Creating a tuple
fruits = ("apple", "banana", "orange", "grape", "kiwi")

# Accessing elements by index
print("Accessing elements by index:")
print("First fruit:", fruits[0])    # Output: apple
print("Third fruit:", fruits[2])    # Output: orange

# Trying to modify a tuple (will result in an error)
# fruits[0] = "pear"  # Uncommenting this line will raise a TypeError

# Unpacking a tuple
first, second, *rest = fruits
print("\nUnpacking a tuple:")
print("First fruit:", first)        # Output: apple
print("Second fruit:", second)      # Output: banana
print("Rest of the fruits:", rest)  # Output: ['orange', 'grape', 'kiwi']

# Concatenating tuples
more_fruits = ("pineapple", "mango")
all_fruits = fruits + more_fruits
print("\nConcatenating tuples:")
print("All fruits:", all_fruits)    # Output: ('apple', 'banana', 'orange', 'grape', 'kiwi', 'pineapple', 'mango')

# Length of the tuple
print("\nLength of the tuple:")
print("Number of fruits:", len(fruits))  # Output: 5

# Checking if an element exists in the tuple
print("\nChecking for element existence:")
print("Is 'banana' in fruits?", "banana" in fruits)  # Output: True
print("Is 'pear' in fruits?", "pear" in fruits)      # Output: False

# Iterating through the tuple
print("\nIterating through the tuple:")
for fruit in fruits:
    print(fruit)

# Slicing a tuple
print("\nSlicing a tuple:")
print("Slice [1:4]:", fruits[1:4])   # Output: ('banana', 'orange', 'grape')

# Attempting to unpack more variables than available (will result in an error)
# a, b, c, d, e, f, g = fruits   # Uncommenting this line will raise a ValueError

# Creating a single-element tuple
single_tuple = ("single",)    # Note the comma after the single element
print("\nCreating a single-element tuple:")
print("Single tuple:", single_tuple)  # Output: ('single',)

Dictionaries

Creating and accessing dictionary elements.


student = {
    "name": "Alice",
    "age": 20,
    "course": "Computer Science"
}

# Accessing values
print("Name:", student["name"])
print("Age:", student["age"])
print("Course:", student["course"])
Output:
Name: Alice
Age: 20
Course: Computer Science

Sets

Working with sets and performing set operations.


numbers = {1, 2, 3, 4, 5}
even = {2, 4, 6, 8}
odd = numbers - even

# Add elements to a set
numbers.add(6)

# Loop through a set
for num in numbers:
    print(num)
Output:
1 2 3 4 5 6


Click this for OOPs in Python

Click this for Exception Handling

Click this for File Handling


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