Python with Mr. Garcia

Python_Tutorial_For_Loops

Understanding for Loops

What is a For Loop?

A for loop is used to repeat a block of code a specific number of times. It is especially useful when working with collections like lists, strings, or ranges of numbers.

How Does a For Loop Work?

A for loop:

Takes each item from a sequence (e.g., a list or range).
Executes the code inside the loop for each item.
Stops when all items are processed.

Basic Syntax

for variable in sequence:

# Code to repeat

Example: Print numbers from 1 to 5

for number in range(1, 6):

print(number)

Output:

Flowchart of a For Loop

Using the range() Function

The range() function is commonly used with for loops to generate a sequence of numbers.

Examples:

range(5) → Counts from 0 to 4 (5 numbers).
range(1, 6) → Counts from 1 to 5.
range(1, 10, 2) → Counts from 1 to 9, skipping by 2.

Code Example:

for number in range(1, 10, 2):

print(number)

Output:

For Loops with Lists

A for loop can iterate through items in a list.

Example:

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

for fruit in fruits:

print(fruit)

Output:

apple

banana

cherry

For Loops with Strings

A for loop can iterate through characters in a string.

Example:

word = "Python"

for letter in word:

print(letter)

Output:

Practice Exercises

Exercise 1: Count to 10

Write a for loop to print numbers from 1 to 10.

Exercise 2: Favorite Colors

Create a list of three favorite colors. Use a for loop to print each color.

Exercise 3: Multiplication Table

Write a program that uses a for loop to print the multiplication table for 5.

Exercise 4: Sum of Numbers

Write a program that calculates the sum of all numbers from 1 to 100 using a for loop.

Exercise 5: Count Characters

Write a program that counts the number of vowels in a string.

Bonus Challenge

Write a program that asks the user to enter 5 numbers, one at a time, and stores them in a list. Use a for loop to calculate and print the average of the numbers.

Congratulations!

You’ve learned the basics of for loops and how to use them with sequences like lists, strings, and ranges. Keep practicing to build your Python skills further! 🎉

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