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Loops in Python are used to execute a block of code multiple times until a specified condition is met. Python provides two primary types of loops: for and while. Additionally, Python offers control statements like break, continue, and pass to manage loop execution efficiently.

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1. The for Loop #

The for loop in Python is used for iterating over a sequence (list, tuple, dictionary, set, or string).

Syntax: #

for variable in sequence:
    # Code to execute

Example: Iterating over a list #

fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(fruit)

Example: Using range() in a for loop #

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

Example: Iterating over a dictionary #

student = {"name": "Alice", "age": 25, "grade": "A"}
for key, value in student.items():
    print(f"{key}: {value}")

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2. The while Loop #

The while loop executes a block of code as long as a specified condition is True.

Syntax: #

while condition:
    # Code to execute

Example: Counting using a while loop #

count = 0
while count < 5:
    print(count)
    count += 1

Example: Using break in a while loop #

num = 1
while num < 10:
    if num == 5:
        break
    print(num)
    num += 1

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3. Loop Control Statements #

a. break Statement #

Terminates the loop when encountered.

for i in range(10):
    if i == 5:
        break
    print(i)

b. continue Statement #

Skips the current iteration and moves to the next.

for i in range(10):
    if i == 5:
        continue
    print(i)

c. pass Statement #

A placeholder used when a statement is syntactically required but no action is needed.

for i in range(5):
    if i == 3:
        pass  # Placeholder for future implementation
    print(i)

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4. Nested Loops #

A loop inside another loop.

for i in range(3):
    for j in range(2):
        print(f"i={i}, j={j}")

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5. List Comprehension with Loops #

Python provides a concise way to create lists using loops.

squares = [x**2 for x in range(5)]
print(squares)

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6. Infinite Loops #

Avoid infinite loops by ensuring the loop condition eventually becomes False.

while True:
    response = input("Type 'exit' to stop: ")
    if response == "exit":
        break

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Conclusion #

Python loops provide an efficient way to automate repetitive tasks. By mastering for and while loops, along with control statements, you can write more efficient and readable code.