I would say to make the while loop act like a for loop.
firstList = [1,2,3]
secondList=[]
counter = len(firstList)-1
while counter >= 0:
secondList.append(firstList[counter])
counter -= 1
Top answer 1 of 3
1
I would say to make the while loop act like a for loop.
firstList = [1,2,3]
secondList=[]
counter = len(firstList)-1
while counter >= 0:
secondList.append(firstList[counter])
counter -= 1
2 of 3
1
The simplest way would be:
def while_version(items):
new_list = []
while items: # i.e. until it's an empty list
new_list.append(items.pop(-1))
return new_list
This will reverse the list:
>>> l1 = [1, 2, 3]
>>> l2 = while_version(l)
>>> l2
[3, 2, 1]
Note, however, that it also empties the original list:
>>> l1
[]
To avoid this, call e.g. l2 = while_version(l1[:]).
Top answer 1 of 5
481
range() and xrange() take a third parameter that specifies a step. So you can do the following.
range(10, 0, -1)
Which gives
[10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
But for iteration, you should really be using xrange instead. So,
xrange(10, 0, -1)
Note for Python 3 users: There are no separate
rangeandxrangefunctions in Python 3, there is justrange, which follows the design of Python 2'sxrange.
2 of 5
279
for x in reversed(whatever):
do_something()
This works on basically everything that has a defined order, including xrange objects and lists.
Reverse while loop python - Stack Overflow
Reversing a while loop. I am having issues grasping the concept of reversing the while loop. Please Help b=1 while b= More on stackoverflow.com
Why isn't my loop iterating backwards in python?
Hint: Look up documentation on the ‘range’ function…does it actually do what you think it does given the two arguments you provided? Maybe you’re missing an argument? https://docs.python.org/3/library/stdtypes.html#range More on reddit.com
13
0
March 8, 2023iterate over a string in reverse
https://docs.python.org/3/library/functions.html#reversed More on reddit.com
7
1
February 7, 2023How to Loop Backwards in Python? - TestMu AI Community
How can I loop backwards from 100 to 0 in Python using a backwards range python? I tried using for i in range(100, 0), but it doesn’t work as expected. How can I fix this to achieve a backward loop? More on community.testmu.ai
0
December 8, 2024Videos
00:44
#Python Reverse a String Using For Loop. - YouTube
Python Tutorial : Reverse a String Using For Loop
02:57
Using reversed to loop in reverse in Python - YouTube
01:35
Loop Over A List In Reverse | Python Example - YouTube
08:02
for Loop - Reversing a Range of Numbers - YouTube
00:16
Reverse a Number in Python using While Loop... #newtum #python ...
DigitalOcean
digitalocean.com › community › tutorials › python-reverse-string
Python Reverse String - 5 Ways and the Best One | DigitalOcean
August 3, 2022 - If you run above Python script, the output will be: ... def reverse_for_loop(s): s1 = '' for c in s: s1 = c + s1 # appending chars in reverse order return s1 input_str = 'ABç∂EF' if __name__ == "__main__": print('Reverse String using for loop =', reverse_for_loop(input_str)) ... def reverse_while_loop(s): s1 = '' length = len(s) - 1 while length >= 0: s1 = s1 + s[length] length = length - 1 return s1 input_str = 'ABç∂EF' if __name__ == "__main__": print('Reverse String using while loop =', reverse_while_loop(input_str))
OneCompiler
onecompiler.com › posts › 3z2wjwde7 › reverse-an-array-list-using-while-loop-python
Reverse an array(list) using while loop Python - Posts - OneCompiler
Step 6: Print reversed list i.e. revArr ... Following is sample Python code. # taking the input from the user to fix the array size size=int(input("Enter the number of elements you want in array: ")) # Create two empty lists arr=[] revArr=[] # adding the elements to the list for i in range(0,size): elem=int(input("Please give value for index "+str(i)+": ")) arr.append(elem) startIndex = 0; lastIndex = size - 1; # iterate the while loop till the lastindex 0 while (lastIndex>=0): revArr.append(arr[lastIndex]) startIndex+=1 lastIndex-=1 # printing the reversed list print("Array in reverse order") for i in range(0,size): print(revArr[i],end=' ')
Know Program
knowprogram.com › home › reverse a number in python using while loop
Reverse a Number in Python using While Loop
December 15, 2021 - Then, find the reverse of a number using the while loop and finally, the result will be displayed on the screen. # Python program to reverse a number using while loop # take inputs num = 12345 # calculate reverse of number reverse = 0 while(num > 0): last_digit = num % 10 reverse = reverse * 10 + last_digit num = num // 10 # display result print('The reverse number is =', reverse)
Newtum
blog.newtum.com › reverse-a-number-in-python-using-while-loop
Reverse a Number in Python Using While Loop - Newtum
April 25, 2024 - # Reverse a Number in python using while Loop # we are taking a number from user as input # entered value will be converted to int from string num = int(input("Enter the number:")) reversed_num = 0 while num != 0: # remainder of the num divided by 10 is stored in the variable digit digit = num % 10 reversed_num = reversed_num * 10 + digit num //= 10 print("Reversed Number: " + str(reversed_num))
GeeksforGeeks
geeksforgeeks.org › python › backward-iteration-in-python
Backward iteration in Python - GeeksforGeeks
July 11, 2025 - a = [1, 2, 3, 4, 5] #Loop through the List # reverse order using slicing(::-1) for item in a[::-1]: print(item) # same logic written using List comprehension # [print(item) for item in a[::-1]] ... Using a while loop provides you control over ...
Python Forum
python-forum.io › thread-26223.html
while loop reading list in reverse
I have written some simple code that should read a list and return a result for each item in the list sandwich_orders = finished_orders = [] print("Sorry we have run out of pastrami") while 'pastrami'
Stack Overflow
stackoverflow.com › questions › 67813959 › reverse-while-loop-python
Reverse while loop python - Stack Overflow
I am having issues grasping the concept of reversing the while loop. Please Help · b=1 while b=<6: d=1 while d<=b: print("1",end="") d+=1 print() b+=1 ... I would recommend cleaning up the indentation. I am guessing you have two nested loops, but as it is written, this won't run in Python.
Reddit
reddit.com › r/learnprogramming › why isn't my loop iterating backwards in python?
r/learnprogramming on Reddit: Why isn't my loop iterating backwards in python?
March 8, 2023 -
Basically, I wanted the loop to start from the last index and work that way done. However, I am not getting anything.
listr = [10,20,30,50]
count = 0
for i in range(len(listr),-1):
count +=1
print(listr[i], count)
print('-----') Top answer 1 of 4
10
Hint: Look up documentation on the ‘range’ function…does it actually do what you think it does given the two arguments you provided? Maybe you’re missing an argument? https://docs.python.org/3/library/stdtypes.html#range
2 of 4
5
range(start, stop, step) if you just give two arguments, the function will interprete it as start and stop.
Reddit
reddit.com › r/learnpython › iterate over a string in reverse
r/learnpython on Reddit: iterate over a string in reverse
February 7, 2023 -
I want to iterate over a string in reverse. I googled it and found this way
for i in range(len(k)-1, 0-1, -1):
but to be honest I don't understand it. can you please explain it to me?
also, I would love it if you guys can suggest other methods
Top answer 1 of 3
6
https://docs.python.org/3/library/functions.html#reversed
2 of 3
2
This is not the approach you should take. reversed linked to by u/PaulRudin is a better tool here. But to explain the code; range takes up to 3 arguments. The first is the starting point. The second is the end point (this value will terminate the iteration and not be yielded back. The third is the step size. This is the amount by which the initial value will be modified by, until it reaches the end value. So if I pass in range(1, 5, 1) I will get back the values: 1, 2, 3, 4 If I was use to range(0, 10, 2) I get: 0, 2, 4, 6, 8 However, using range(10, 0, -2) gives 10, 8, 6, 4, 2 In this code you are starting from the end of some string (the length less one to get the last index) and taking steps backwards by 1 each iteration. The end point is -1 to include the 0 index (written strangely here, but this is a slightly strange construct anyway).
Mimo
mimo.org › glossary › python › for-loop
Python For Loop: Syntax and Examples [Python Tutorial]
You can achieve this with the ... enumerate(fruits): print(f"Index {index}: {fruit}") You can loop over a sequence in reverse order by using the reversed() Python function....
Codecademy
codecademy.com › article › how-to-reverse-a-list-in-python
How to Reverse a List in Python | Codecademy
You can use slicing ([::-1]), ... You can reverse a list using a while loop by swapping elements from the start and end of the list until the two pointers meet in the middle....
Python Morsels
pythonmorsels.com › looping-in-reverse
Looping in reverse - Python Morsels
May 27, 2025 - But for iterables that can be reversed, you can use the built-in reversed function to loop backward. ... We don't learn by reading or watching. We learn by doing. That means writing Python code.
TestMu AI Community
community.testmu.ai › ask a question
How to Loop Backwards in Python? - TestMu AI Community
December 8, 2024 - How can I loop backwards from 100 to 0 in Python using a backwards range python? I tried using for i in range(100, 0), but it doesn’t work as expected. How can I fix this to achieve a backward loop?
Medium
medium.com › @shaikshabbeer643 › write-a-python-program-to-reverse-a-given-positive-integer-using-a-while-loop-7e9b693fedc0
Write a Python program to reverse a given positive integer using a while loop. | by Shaik Shabbeer | Medium
May 14, 2025 - while n > 0: r = n % 10 # Extract the last digit rev = (rev * 10) + r # Build the reversed number n = n // 10 # Remove the last digit print(rev) # Output: 4321 ... 4th Pass1 > 0 (True)r = 1 % 10 = 11 rev = (432 * 10) + 1 = 43211 // 10 = 05th Pass0 > 0 (False)Loop stops--
Programiz
programiz.com › python-programming › examples › reverse-a-number
Python Program to Reverse a Number
To understand this example, you should have the knowledge of the following Python programming topics: ... num = 1234 reversed_num = 0 while num != 0: digit = num % 10 reversed_num = reversed_num * 10 + digit num //= 10 print("Reversed Number: " + str(reversed_num))
Reddit
reddit.com › r/learnpython › how to reverse a list of numbers using while loop?
r/learnpython on Reddit: how to reverse a list of numbers using while loop?
February 18, 2021 -
e.g [3,6,5,1,4,14] into [14,4,1,5,6,3]
I thought I could first use min/max values but I don't think they will work as the list is unsorted.
Any help is appreciated
Top answer 1 of 3
2
I'll leave the coding part to you, just give you some idea how to do it: Swap the first one with last one. Swap the second one with second to last ... Continue swapping like that till you get to the middle of the list (WHILE not in middle). Once you reach middle, you swapped all of them (except maybe the one in the middle, if you have odd number of elements).
2 of 3
2
Do you have to use for loops? Because you can just use my_list.reverse()
Top answer 1 of 4
7
Python string is not mutable, so you can not use the del statement to remove characters in place. However you can build up a new string while looping through the original one:
def reverse(text):
rev_text = ""
for char in text:
rev_text = char + rev_text
return rev_text
reverse("hello")
# 'olleh'
2 of 4
6
The problem is that you can't use del on a string in python.
However this code works without del and will hopefully do the trick:
def reverse(text):
a = ""
for i in range(1, len(text) + 1):
a += text[len(text) - i]
return a
print(reverse("Hello World!")) # prints: !dlroW olleH
OpenClass
open.openclass.ai › resource › assignment-630598c789f3aa2789eaf0bc › question-630598c789f3aa2789eaf061 › feedback › share
Reverse the a given integer using a while loop Use one of the following numbers to test your code: 123,456,789 Expected output: 123 Reverse Number 321 - Making Decisions and Repeating Instructions Practice - Use this assignment in your class! - OpenClass
Python · You passed all test cases! STDIN · 123 · Expected STDOUT · Reverse Number 321 · Your STDOUT · Reverse Number 321 · STDIN · 456 · Expected STDOUT · Reverse Number 654 · Your STDOUT · Reverse Number 654 · STDIN · 789 · Expected STDOUT ·