What is the syntax for range () function in python?

Question

❮ Built-in Functions

Example

Create a sequence of numbers from 0 to 5, and print each item in the sequence:

x = range(6)
for n in x:
print(n)

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Definition and Usage

The range() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and stops before a specified number.

Syntax

Parameter Values

Parameter	Description
start	Optional. An integer number specifying at which position to start. Default is 0
stop	Required. An integer number specifying at which position to stop (not included).
step	Optional. An integer number specifying the incrementation. Default is 1

More Examples

Example

Create a sequence of numbers from 3 to 5, and print each item in the sequence:

x = range(3, 6)
for n in x:
print(n)

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Example

Create a sequence of numbers from 3 to 19, but increment by 2 instead of 1:

x = range(3, 20, 2)
for n in x:
print(n)

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❮ Built-in Functions

The range() function returns a sequence of numbers between the give range.

Example

# create a sequence of numbers from 0 to 3
numbers = range(4)

# iterating through the sequence of numbers
for i in numbers:
    print(i)

# Output:

# 0
# 1
# 2
# 3

Note: range() returns an immutable sequence of numbers that can be easily converted to lists, tuples, sets etc.

Syntax of range()

The range() function can take a maximum of three arguments:

range(start, stop, step)

The start and step parameters in range() are optional.

Now, let's see how range() works with different number of arguments.

Example 1: range() with Stop Argument

If we pass a single argument to range(), it means we are passing the stop argument.

In this case, range() returns a sequence of numbers starting from 0 up to the number (but not including the number).

# numbers from 0 to 3 (4 is not included)
numbers = range(4)
print(list(numbers))    # [0, 1, 2, 3]

# if 0 or negative number is passed, we get an empty sequence
numbers = range(-4)
print(list(numbers))    # []

Example 2: range() with Start and Stop Arguments

If we pass two arguments to range(), it means we are passing start and stop arguments.

In this case, range() returns a sequence of numbers starting from start (inclusive) up to stop (exclusive).

# numbers from 2 to 4 (5 is not included)
numbers = range(2, 5)
print(list(numbers))    # [2, 3, 4]

# numbers from -2 to 3 (4 is not included)
numbers = range(-2, 4)    
print(list(numbers))    # [-2, -1, 0, 1, 2, 3]

# returns an empty sequence of numbers
numbers = range(4, 2) 
print(list(numbers))    # []

Example 3: range() with Start, Stop and Step Arguments

If we pass all three arguments,

the first argument is start
the second argument is stop
the third argument is step

The step argument specifies the incrementation between two numbers in the sequence.

# numbers from 2 to 10 with increment 3 between numbers
numbers = range(2, 10, 3)
print(list(numbers))    # [2, 5, 8]

# numbers from 4 to -1 with increment of -1
numbers = range(4, -1, -1)    
print(list(numbers))    # [4, 3, 2, 1, 0]

# numbers from 1 to 4 with increment of 1
# range(0, 5, 1) is equivalent to range(5)
numbers = range(0, 5, 1) 
print(list(numbers))    # [0, 1, 2, 3, 4]

Note: The default value of start is 0, and the default value of step is 1. That's why range(0, 5, 1) is equivalent to range(5).

range() in for Loop

The range() function is commonly used in a for loop to iterate the loop a certain number of times. For example,

# iterate the loop 5 times
for i in range(5):
    print(i, 'Hello')

0 Hello
1 Hello
2 Hello
3 Hello
4 Hello

Learn about the Python Range() function and its capabilities

Photo by Kay on Unsplash

Introduction

The range() is an in-built function in Python. It returns a sequence of numbers starting from zero and increment by 1 by default and stops before the given number.

Now that we know the definition of range, let’s see the syntax:

range(start, stop, step)

It has three parameters, in which two are optional:

start: It’s an optional parameter used to define the starting point of the sequence. By default, it’s zero.
stop: It’s a mandatory parameter, used to define the stopping point of the sequence
step: It’s also an optional parameter used to specify the incrementation on each iteration; by default, the value is one.

General Usage

As it returns a sequence of numbers, most of the developers use the range to write loops. This comes handy when you don’t have a list or tuple, but only a specific value to implement the loop.

Variation One

Here we will implement a for loop with only one parameter — stop value.

Here x is the range that we used to implement the loop, and n is the value in each iteration. Observe that the output ends before the stop value; it is never a part of the range iteration similar to list.size().

Variation Two

Here we will implement the for loop using start and stop as parameters.

Variation Three

Now, we will use all three parameters: start, stop and step. Have a look:

As the step value is 2, instead of incrementing by 1, the loop increment by 2 on each iteration. One of the important things that we need to keep in mind is the step value should never be zero; else, It will throw a ValueError exception.

Iteration over list types

Along with loops, range() is also used to iterate over the list types using the len function and access the values through the index. Have a look:

Reverse Range

We can give either positive or negative numbers for any of the parameters in the range. This feature offers the opportunity to implement reverse loops. We can do this by passing a higher index as a start and a negative step value. Have a look:

Create List, Set and Tuple using Range

range() comes handy in many situations, rather than only using to write loops. For example, we create List, Set, and Tuple using range function instead of using loops to avoid boilerplate code. Have a look:

To make it a bit more fun, we can pass negative values in step to create ascending order lists. Have a look:

Indexing Range

Like the way we access values in the list using the index, we can do the same for range. The syntax is also similar to list index access.

Float Arguments in Range

By default, the range() function only allow integers as parameters. If you pass flow value, then it throws the following error:

TypeError: 'float' object cannot be interpreted as an integer

But there is a workaround for this; we can write a custom Python function similar to the one below. It will allow you to specify a float value for the step argument.

That is all for now, hope you learned something useful, thanks for reading.

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What is range () function write the syntax give an example?

Use a negative step value in a range() function to generate the sequence of numbers in reverse order. For example, range(5, -,1, -1) will produce numbers like 5, 4, 3, 2, and 1. I.e., you can reverse a loop by setting the step argument of a range() to -1. It will cause the for loop to iterate in reverse order.

What is range () in Python give an example to explain it?

Example 1: range() with Stop Argument If we pass a single argument to range() , it means we are passing the stop argument. In this case, range() returns a sequence of numbers starting from 0 up to the number (but not including the number).

What type is range ()?

Python range() Method The range() constructor method returns an object of the range class, which is an immutable sequence type. The range() method returns the immutable sequence numbers between the specified start and the stop parameter, increment by step parameter.

What is the purpose of range () function give one example?

One of the most common uses of the range() function is for iterating over a series of values in a for loop. This is particularly useful if you want to access each of the values in a list or array, or, for example, only every other value. In this example, the range() function is generating a sequence from 0 to 4 .

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