A for loop in Python is used to iterate over a sequence (like a list, tuple, string, or range). It allows you to execute a block of code repeatedly for each item in the sequence. Here’s a detailed explanation of the for loop with a simple example.

Syntax

for item in sequence:
    # Block of code to be executed for each item

• item: The variable that takes the value of the current element in the sequence during each iteration.
• sequence: The sequence (like a list, tuple, string, or range) that you are iterating over.

Example 1: Iterating Through a List

Let’s use a simple example to illustrate a for loop. We’ll iterate through a list of fruits and print each fruit.

fruits = ["apple", "banana", "cherry"]

for fruit in fruits:
    print(fruit)

Output:

apple
banana
cherry

In this example, the for loop iterates through each item in the fruits list. The fruit variable takes the value of each item in the list during each iteration, and the print(fruit) statement prints the current value of fruit.

Example 2: Iterating Through a String

You can also use a for loop to iterate through the characters in a string.

for char in "hello":
    print(char)

Output:

h
e
l
l
o

In this example, the for loop iterates through each character in the string "hello". The char variable takes the value of each character during each iteration, and the print(char) statement prints the current character.

Example 3: Using range()

The range() function generates a sequence of numbers, which can be used to control the number of times a for loop executes.

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

Output:

0
1
2
3
4

In this example, the range(5) function generates a sequence of numbers from 0 to 4. The for loop iterates through these numbers, and the print(i) statement prints the current value of i.

Example 4: Iterating Through a Dictionary

You can also use a for loop to iterate through the keys or key-value pairs of a dictionary.

person = {"name": "Alice", "age": 25, "city": "New York"}

# Iterating through keys
for key in person:
    print(key)

# Iterating through key-value pairs
for key, value in person.items():
    print(f"{key}: {value}")

Output:

name
age
city
name: Alice
age: 25
city: New York

In this example, the first for loop iterates through the keys of the person dictionary and prints each key. The second for loop uses the items() method to iterate through the key-value pairs and prints each key along with its corresponding value.

Summary

• for loop: Used to iterate over a sequence (like a list, tuple, string, or range).
• Syntax: for item in sequence:
• Common Uses: Iterating through lists, strings, ranges, and dictionaries.