Python strings are immutable, which means you can't really change it. There's no way you could reverse it in-place.
Obviously, you could reassign the same variable to it, but this is not an in-place change as you asked for:
str = 'reverse'
str = str[::-1]
Answer from Vitor Falcão on Stack OverflowWhy does [::1] reverse a string in Python?
7 proven methods to reverse the python string in 2021
Why does this not reverse a string in place?
It's supposedly a list, not string, and it should be getting reversed in place. It just gets reversed twice, so it ends up in the original order.
Try len(s) // 2
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For example:
txt = "Hello World"[::-1]
Isn't the splice syntax [start : stop: step]? And default of start and stop are the beginning and end of the string? So that would make the above start at the beginning, stop at the end, but step by -1. That feels like it would start at the beginning, then step backwards to...before the beginning of the string?
Sorry for the silly question, I just can't figure out why this syntax works the way it does.
How to reverse the python string now in 2021?
Hello to all python buddies,
You're stirring your cofee, and going to read r/Python. And you love the blog post.
Today, I'm going to make r/Python more lovable to you.
I'm going to show you the 6 proven methods to reverse the python string. Which are easy and quick to do.
So, start these methods
☺️
Reverse the string using slice method
You can reverse the string using slice method.
The slice indicates the [start:end] position.
A start is a position where sequence start. and end is the position where sequence ends.
The first position is 0th index.
So, here you can use [::-1].
The [::-1] means sequence starting from last of the string.
For example,
a = ["hello"]
print(a[::-1])
It'll reverse the python string.
>>> olleh
2. Reversed the string using reversed() &join() methods
First of all, the reversed() method reverse the sequence.
After reversed() with you can join() every iterables as string.
Basically, the join() method join the iterables as a string seperator.
reversed() & join()After running, this code you'll get something like
👇
output3. Reversed the string: join() and sorted() method
As you know, sorted() sort the string or sequences in ascending or descending method.
Here, I'm going to use descending order.
For descending order, pass reverse = True inside sorted().
And previously, I've told that join joins the sequences as a string seperator.
For example,
join() & sorted()Here, you can see that first I've sorted the string in descending order.
After that, I've join every character as a string.
When you run above code, you'll get:--->
outputSo, you've get the reversed string as output.
4. Reversed the string using for loop
You can reverse the string using for loop.
To create the reverse string in for loop, you need function with empty string.
The every new string add to the empty string.
After adding, all the string it becomes the reverse string.
For example,
codeAfter running code, you'll get--->
outputSo, here you've seen how to reverse the python string. I've told you the 6 methods.
And here I've shown you the 4 methods.
But I'm going to show you 3 methods more.
That means 7 method for reverse the python string.
So, I've given you 1 bonus method.
To get these 3 methods, check out the
👇
https://www.heypython.com/python-programming/reverse-the-python-string/
def reverseString(self, s: List[str]) -> None:
for i in range(len(s)):
s[i],s[len(s)-1-i]=s[len(s)-1-i],s[i]