range() Function

Understanding range()

The range() function in Python generates a sequence of numbers. It's commonly used for iterating over a specific number of times using for loops.

Syntax

Python

range(stop)

range(start, stop, step)

Use code with caution.

Parameters

• stop: Required. The sequence ends at stop - 1.

• start: Optional. The sequence starts at start. Default is 0.

• step: Optional. The difference between each number in the sequence. Default is 1.

Examples

Python

# Basic usage

numbers = range(5)

print(list(numbers))  # Output: [0, 1, 2, 3, 4]

# Starting from 2, ending at 10, with a step of 2

numbers = range(2, 10, 2)

print(list(numbers))  # Output: [2, 4, 6, 8]

# Counting backwards

numbers = range(10, 0, -2)

print(list(numbers))  # Output: [10, 8, 6, 4, 2]

Use code with caution.

Important Points

• range() returns an immutable sequence object, not a list. To convert it to a list, use list(range(...)).

• The stop value is exclusive, meaning it's not included in the generated sequence.

• The step can be negative to create a decreasing sequence.

Common Use Cases

• Iterating over a sequence of numbers in a for loop.

• Creating lists of numbers.

• Generating indices for accessing elements in other sequences.

Example with a for loop

Python

for i in range(5):

    print(i)

Use code with caution.

In essence, range() is a versatile function for creating sequences of numbers, which is often used in conjunction with loops for repetitive tasks.