Python range() Function

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Python range() Function

The built-in range() function generates an immutable sequence of numbers. It is most commonly used in loops when you need to repeat an action a specific number of times.

The object returned by range() has its own data type called range.

Immutable means the sequence cannot be changed after it is created.

Creating a Range

The general syntax of the range() function is:

range(start, stop, step)

    • start → starting value (inclusive, optional)

    • stop → ending value (exclusive, required)

    • step → difference between values (optional, default is 1)

Using range() with One Argument

When only one argument is provided, it represents the stop value.

The sequence automatically starts from 0.

nums = range(8) print(list(nums))

Output:

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

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Using range() with Two Arguments

With two arguments, the first is the start, and the second is the stop.

nums = range(4, 9) print(list(nums))

Output:

[4, 5, 6, 7, 8]

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Using range() with Three Arguments

The third argument defines the step size, which controls how much each value increases (or decreases).

nums = range(2, 15, 3) print(list(nums))

Output:

[2, 5, 8, 11, 14]

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Using range() in Loops

The range() function is widely used with for loops.

for number in range(5): print("Count:", number)

Output:

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

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Converting a Range to a List

A range object does not directly display all its values.

To see the full sequence, convert it into a list.

print(list(range(3))) print(list(range(2, 7))) print(list(range(1, 12, 4)))

Output:

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

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Indexing and Slicing Ranges

Ranges behave like other sequences and support indexing and slicing.

r = range(12) print(r[4]) # Access a single element print(list(r[1:6])) # Slice a range

Output:

4
[1, 2, 3, 4, 5]

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Note:

    • Indexing returns a single value

    • Slicing returns a new range object

Checking Membership with in

You can check whether a value exists in a range using the in keyword.

even_nums = range(0, 20, 2) print(10 in even_nums) print(11 in even_nums)

Output:

True
False

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Finding the Length of a Range

The len() function returns how many numbers exist in a range.

r = range(1, 20, 3) print(len(r))

Output:

7

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