๐ Introduction to Loops in Python
In Python, a loop is a way to repeat a block of code multiple times. Setting the number of repetitions is crucial for controlling how many times the loop executes. Let's explore how to do this using for loops and the range() function.
๐ History and Background
The concept of loops has been around since the early days of computing. They are fundamental in programming because they allow computers to automate repetitive tasks. Python, designed for readability, makes loops easy to understand and use.
๐ Key Principles
The primary method for setting loop repetitions in Python involves the for loop and the range() function. The range() function generates a sequence of numbers, and the for loop iterates through this sequence.
- ๐ข Using
range(): The range() function can take one, two, or three arguments: range(stop), range(start, stop), and range(start, stop, step).
- ๐ Basic Repetition:
for i in range(5): will repeat the loop 5 times, with i taking values from 0 to 4.
- ๐ Custom Range:
for i in range(2, 7): will repeat the loop from 2 to 6.
- ๐ถ Step Size:
for i in range(0, 10, 2): will repeat the loop with values 0, 2, 4, 6, and 8.
๐ป Real-world Examples
Example 1: Printing Numbers
This code prints numbers from 0 to 4.
for i in range(5):
print(i)
Example 2: Printing a Message Multiple Times
This code prints "Hello, World!" three times.
for i in range(3):
print("Hello, World!")
Example 3: Using a Custom Range
This code prints numbers from 10 to 14.
for i in range(10, 15):
print(i)
Example 4: Using a Step Size
This code prints even numbers from 0 to 8.
for i in range(0, 10, 2):
print(i)
๐งฎ Practice Quiz
- โ What will the following code print?
for i in range(4):
print("*")
- โ What will the following code print?
for i in range(1, 6):
print(i + 1)
- โ What will the following code print?
for i in range(5, 0, -1):
print(i)
๐ก Conclusion
Understanding how to set loop repetitions is fundamental in Python. By using the for loop with the range() function, you can easily control how many times a block of code is executed. This is a powerful tool for automating tasks and writing efficient programs. Keep practicing, and you'll master loops in no time!