Python range Function – How to Use It [With Examples]

The Python range() function returns an immutable sequence of integers between a given start and endpoint, incrementing by a given amount.

Python range Syntax

Here’s the syntax for the Python range() function:

range(start, stop, step)

Note that:

• start is the integer to start incrementing from – it will be included in the range
  • If it is not supplied, it will be assumed to be 0
• stop is the integer to end the range at – it will NOT be included in the range – the range will end before the stop value
  • If start and stop are the same, an empty range will be returned
• step is the integer amount each value in the range is incremented by
  • Defaults to 1 if not specified
• Only integers are supported for all values
• The range() function will return an immutable sequence of integer values
  • Immutable means that the contents of the sequence cannot be changed

Examples

Here are some examples for using the range() function:

Creating and Looping Over a Range of Integers from 0 to 4

myRange = range(4)
for myNum in myRange:
    print(myNum)

Note that: – The result of the range() function has been assigned to the variable myRange – Each value in the generated range is assigned to the loop variable myNum and printed using a python for statement – As no start or step have been specified for the range() function, they have defaulted to 0 and 1 respectively

The above example will output:

0
1
2
3

Creating and Looping Over a Range of Integers from 10 to 30, in Increments of 5

myRange = range(10, 30, 5)
for myNum in myRange:
    print(myNum)

Note that:

• We have supplied start, stop and step values to the range() function

The above example will output:

10
15
20
25

Creating and Looping Over a Range of Integers from 50 to 30, Decrementing by 2

Negative integers can also be supplied. Using a negative step will decrement instead of incrementing when generating the range values.

myRange = range(50, 40, -2)
for myNum in myRange:
    print(myNum)

The above example will output:

50
48
46
44
42

Conclusion

Creating a range of numbers can be useful for looping over a series of known values or an array of a known size. Looping over a range can be used to perform actions on each value in the range, simplifying making calculations.

For more information on Python, Python functions and behavior, and projects to get you started, check out our other Python articles!