Pythonループの練習: カンタンに使える効果的な方法

[

Python Loops Practice

Introduction

In this tutorial, we will learn about loops in Python and how to use them effectively. Loops are a fundamental concept in programming that allow us to repeat a block of code multiple times. By the end of this tutorial, you will have a solid understanding of how loops work and how to apply them in your own Python programs.

Table of Contents

1. What are Loops?
2. Types of Loops in Python
   • For Loop
   • While Loop
3. Loop Control Statements
   • Break Statement
   • Continue Statement
4. Practical Examples
5. Conclusion

What are Loops?

Loops are a way to repeatedly execute a block of code until a certain condition is met. They save time and effort by automating repetitive tasks. Instead of writing the same code multiple times, we can use loops to iterate over a sequence of elements and perform the same action on each element.

Types of Loops in Python

For Loop

The for loop in Python is used to iterate over a sequence (such as a list, tuple, or string) or other iterable objects. It allows us to perform a set of actions for each element in the sequence.

Here is the basic syntax of a for loop:

for element in sequence:
    # code to be executed for each element

Let’s see an example that demonstrates the usage of a for loop:

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

for fruit in fruits:
    print(fruit)

Output:

apple
banana
cherry

While Loop

The while loop in Python is used to execute a block of code as long as a certain condition is true. It continues to iterate until the condition becomes false.

Here is the basic syntax of a while loop:

while condition:
    # code to be executed

Let’s see an example that demonstrates the usage of a while loop:

count = 0

while count < 5:
    print(f"Count: {count}")
    count += 1

Output:

Count: 0
Count: 1
Count: 2
Count: 3
Count: 4

Loop Control Statements

Python provides two loop control statements to modify the behavior of loops, namely the break statement and the continue statement.

Break Statement

The break statement is used to exit the current loop prematurely. When the program encounters a break statement inside a loop, it immediately exits the loop and continues with the next statement after the loop.

Here is an example that demonstrates the usage of a break statement:

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

for fruit in fruits:
    if fruit == 'banana':
        break
    print(fruit)

Output:

apple

Continue Statement

The continue statement is used to skip the remaining code in the current iteration of a loop and move to the next iteration. It allows us to ignore certain elements and continue with the next iteration.

Here is an example that demonstrates the usage of a continue statement:

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

for fruit in fruits:
    if fruit == 'banana':
        continue
    print(fruit)

Output:

apple
cherry

Practical Examples

Now let’s look at some practical examples to further understand the usage of loops in Python.

Example 1: Sum of Numbers

numbers = [1, 2, 3, 4, 5]
sum = 0

for number in numbers:
    sum += number

print(f"The sum is: {sum}")

Output:

The sum is: 15

Example 2: Factorial of a Number

number = 5
factorial = 1

while number > 0:
    factorial *= number
    number -= 1

print(f"The factorial is: {factorial}")

Output:

The factorial is: 120

Conclusion

In this tutorial, we learned about loops in Python and how to use them effectively. We explored the for loop and the while loop, as well as the break and continue statements. By practicing with various examples, you have gained hands-on experience in using loops to automate repetitive tasks. Keep practicing and experimenting with loops to enhance your Python programming skills.