The range() Function
In Python, the range()
function is a powerful tool for generating a sequence of numbers. It is commonly used with loops to iterate over a range of values efficiently.
Understanding range()
The range()
function produces a sequence of numbers, starting from a specified value (default is 0) and ending before a specified stop value. It follows this syntax:
range(start, stop, step)
- start (optional): The beginning number (default is
0
). - stop (required): The number where the sequence stops (not included).
- step (optional): The increment between each number (default is
1
).
Examples
Basic Usage
for i in range(5): # Generates numbers from 0 to 4
print(i)
Output:
0
1
2
3
4
Using start
and stop
for i in range(2, 7): # Generates numbers from 2 to 6
print(i)
Output:
2
3
4
5
6
Using step
for i in range(1, 10, 2): # Generates numbers from 1 to 9 with a step of 2
print(i)
Output:
1
3
5
7
9
Counting Backwards
for i in range(10, 0, -2): # Counts down from 10 to 2, decreasing by 2 each time
print(i)
Output:
10
8
6
4
2
Converting range()
to a List
If you want to see the values of range()
at once, you can convert it to a list:
print(list(range(5)))
Output:
[0, 1, 2, 3, 4]
Exercise: Try It Yourself!
- Create a loop that prints the numbers from 5 to 15 using
range()
. - Write a loop using
range()
that prints all even numbers between 2 and 20. - Generate a countdown from 10 to 1 using
range()
.