Python Program to Print Numbers in a Range (1,upper) Without Using any Loops

When it is required to print numbers in a given range without using any loop, we can use recursion. This technique involves defining a function that calls itself with a decremented value until it reaches the base case.

Below is the demonstration of the same ?

Example

def print_nums(upper_num):
    if(upper_num > 0):
        print_nums(upper_num - 1)
        print(upper_num)

upper_lim = 6
print("The upper limit is :")
print(upper_lim)
print("The numbers are :")
print_nums(upper_lim)

Output

The upper limit is :
6
The numbers are :
1
2
3
4
5
6

How It Works

The function uses recursion to achieve the loop-like behavior:

• The function print_nums checks if the number is greater than 0

• If true, it calls itself with upper_num - 1

• This continues until the base case (upper_num = 0) is reached

• Then it prints the numbers in ascending order as the recursion unwinds

Alternative Implementation

You can also print numbers in descending order by placing the print statement before the recursive call ?

def print_nums_desc(upper_num):
    if(upper_num > 0):
        print(upper_num)
        print_nums_desc(upper_num - 1)

upper_lim = 5
print("Numbers in descending order:")
print_nums_desc(upper_lim)

Numbers in descending order:
5
4
3
2
1

Conclusion

Recursion provides an elegant way to print numbers in a range without using loops. The key is understanding how the recursive calls stack and unwind to achieve the desired output order.