Introduction to Python Range Function

# Introduction to Python Range Function

Vikram Singh
Assistant Manager - Content
Updated on Jun 12, 2023 11:01 IST

The range function in Python returns a sequence of numbers starting from the given input value (by default: 0), increments the number at the defined step size (by default: 1), and stops before the specified value. In this article, we will discuss python range function, and how to use them.

Python offers a number of built-in functions and types that are always available to use. In this article, we will discuss one such built-in function that represents an immutable sequence of numbers and is commonly used for looping a specific number of times in the for loops.

Must Read: For Loop in Python (Practice Examples)

Must Check: Python Online Course and Certification

## What is Python Range Function?

Definition

The range function in Python returns a sequence of numbers starting from the given input value (by default: 0), increments the number at the defined step size (by default: 1), and stops before the specified value.

• range () functions are most commonly used for loops to iterate sequences on a sequence of numbers.
• range () function only takes integer values.
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Syntax

`range (start, stop, step_size)Copy code`

Parameter

• start: the value from where the sequence will start.
• It is optional.
• If not defined, the value starts from 0.
• stop: the next value after the sequence will stop.
• Not optional.
• step_size: denotes the difference between two values, i.e., how much we have to add to get the next value.
• It is optional.
• If not defined, the step_size will be 1.
• The value should be an integer value (whole number)
• if step_size = 0, it will throw an error.

## How to use the Python Range function?

Python range() functions are used in three different formats, depending on the number of parameters used at a time.

• range (stop)

range (stop) function will return the list of values from 0 to stop โ 1. It will take only positive values.

• range(stop) function considers only positive integers
• If you input a floating value (or any other data type in Python), it will return a TypError.
• If we input a negative value, it will show nothing.

Letโs take some examples:

Example 1:

`#print the first 10 whole numbernumber = range(10)print(list(number))Copy code`

Output

Example 2:

```#print the first 10 integers using for loop for i in range(10): print(i, end =" ")print()Copy code```

Output

Example 3

```#using a negative value for the stop for i in range(-10): print(i, end =" ")print()Copy code```

Output

nothing

Example 4

`#using a floating value for the stopfor i in range(10.5): print(i, end =" ")print()Copy code`

Output

• range (start, stop)

Here, we will use two parameters (or arguments) with the range() function, i.e., start and stop. As a result, we will get the sequence of integers as a start, start + 1, start + 2, start + 3, โฆโฆ., stop -1

Note: Here, the start and stop values can be either positive or negative.

Letโs move to examples:

Example โ 1:

`# start and stop both are positive#list the number of integers between 5 to 10.for i in range(5, 10): print(i, end =" ")print()Copy code`

Output

Example โ 2

`# start = -ve & stop = +ve#list the number of integers between -5 to 10.for i in range(-5, 10): print(i, end =" ")print()Copy code`

Output

Example -3

`#start and stop both are negative#list the number of integers between -10 to -5.for i in range(-10, -5): print(i, end =" ")print()Copy code`

Output

• range (start, stop, step_size)

Here, we will use all three parameters with the range function, i.e., start, stop, and step size.

• It is used when we donโt want to traverse an iterable sequentially but want to access every n-th value of the sequence.
•  range(start, stop, step_size) will produce a sequence such as:

start, start + step, start + 2*step, start + 3*step, โฆโฆ., start + n *step

where,

start + n*step < stop < start + (n+1) step.

• Here, the value of step size can be negative.
• In this case, start > stop.

Letโs take some examples:

Example-1:

`#list the number of integers between 0 to 20 at the step size of 2for i in range (0, 20, 2): print(i, end =" ")print()Copy code`

Output

Example -2

`#negative step-size#lsit the number of integers between 0 to 20 at the step size of -2for i in range (20, 0, -2): print(i, end =" ")print()Copy code`

Output

## Reversed Range

How will you reverse the output produced by the range() function?

In Python, we can do it in two ways:

• By negative step size (step size = -1)
• By reverse function
• reversed (range()) function displays the sequence of numbers produced by the range() function in descending or reversed order.

Letโs take an example to know how it works:

`#using reversed function#lsit the number of integers (in decreasing order) between 0 to 20 at the step size of 2for i in reversed(range (0, 20, 2)): print(i, end =" ")print()Copy code`

Output

## Conclusion

In this article, we have briefly discussed the range () function in Python, with examples of how it works in different conditions.
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Vikram Singh
Assistant Manager - Content

Vikram has a Postgraduate degree in Applied Mathematics, with a keen interest in Data Science and Machine Learning. He has experience of 2+ years in content creation in Mathematics, Statistics, Data Science, and Mac... Read Full Bio