Python range() Function

The range() function in Python is used to generate a sequence of numbers. It is particularly useful for looping a specific number of times in for loops. The range() function generates an immutable sequence of numbers, which can be iterated over.

Table of Contents

1. Introduction
2. range() Function Syntax
3. Understanding range()
4. Examples
   • Basic Usage
   • Using range() with Different Start and End Values
   • Using range() with a Step Value
5. Real-World Use Case
6. Conclusion

Introduction

The range() function generates a sequence of numbers. It is widely used in for loops to iterate over a sequence of numbers efficiently. The generated sequence can be specified by a start, stop, and step value.

range() Function Syntax

The syntax for the range() function is as follows:

range(stop)
range(start, stop[, step])

Parameters:

• start (optional): The starting value of the sequence (inclusive). Defaults to 0.
• stop: The end value of the sequence (exclusive).
• step (optional): The difference between each pair of consecutive values. Defaults to 1.

Returns:

• An immutable sequence of numbers.

Understanding range()

The range() function returns an immutable sequence of numbers starting from the start value to the stop value, incremented by the step value. If only the stop value is provided, the sequence starts from 0 and ends at stop - 1.

Examples

Basic Usage

To demonstrate the basic usage of range(), we will generate a sequence of numbers from 0 to 4.

Example

# Generating a range of numbers from 0 to 4
for i in range(5):
    print(i)

Output:

0
1
2
3
4

Using range() with Different Start and End Values

This example shows how to generate a sequence of numbers with a specified start and end value.

Example

# Generating a range of numbers from 2 to 5
for i in range(2, 6):
    print(i)

Output:

2
3
4
5

Using range() with a Step Value

This example demonstrates how to generate a sequence of numbers with a specified step value.

Example

# Generating a range of numbers from 1 to 10 with a step of 2
for i in range(1, 11, 2):
    print(i)

Output:

1
3
5
7
9

Real-World Use Case

Looping Over Indices

In real-world applications, the range() function is often used to loop over the indices of a list.

Example

# Looping over the indices of a list
fruits = ['apple', 'banana', 'cherry']
for i in range(len(fruits)):
    print(f"Index {i}: {fruits[i]}")

Output:

Index 0: apple
Index 1: banana
Index 2: cherry

Creating Lists

The range() function can be used to create lists of numbers.

Example

# Creating a list of numbers from 0 to 9
numbers = list(range(10))
print(numbers)

Output:

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Generating Even or Odd Numbers

The range() function can also be used to generate sequences of even or odd numbers.

Example

# Generating even numbers from 0 to 10
even_numbers = list(range(0, 11, 2))
print("Even numbers:", even_numbers)

# Generating odd numbers from 1 to 10
odd_numbers = list(range(1, 11, 2))
print("Odd numbers:", odd_numbers)

Output:

Even numbers: [0, 2, 4, 6, 8, 10]
Odd numbers: [1, 3, 5, 7, 9]

Conclusion

The range() function in Python is a versatile tool for generating sequences of numbers. By using this function, you can create ranges of numbers with specified start, stop, and step values. This function is particularly helpful in scenarios such as looping over a sequence of numbers, creating lists of numbers, and generating even or odd number sequences in your Python applications.