Reversing string in python using assignment of strings

Question

def reverse(text):
    length = len(text)
    length -= 1
    a = ''
    for pos in range(length/2):
        a[pos] = text[length]
        text[pos] = a[pos]
        length -= 1
    print text

While I was coding in codecademy I typed this code and found the error which is:

Does your reverse function take exactly one argument (a string)? Your code threw a "'str' object does not support item assignment" error.

which step am I doing wrong? how to proceed without using .join() or any in-built?

Strings are immutable, you can't assign to a character by index. — jonrsharpe
– jonrsharpe, Commented Feb 15, 2016 at 20:44
strings are immutable so you cannot use assignment as you would a list, why not just concat to a starting in range len(s) down ? — Padraic Cunningham
– Padraic Cunningham, Commented Feb 15, 2016 at 20:44
It looks like you expect this to be swapping characters in your string; even if strings were mutable, this wouldn't accomplish that. — Scott Hunter
– Scott Hunter, Commented Feb 15, 2016 at 20:47

Thomas Lotze · Accepted Answer · 2016-02-15 21:20:40Z

2

It's as simple as this:

text[::-1]

answered Feb 15, 2016 at 21:20

Thomas Lotze

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2 Comments

Mann Over a year ago

I am not allowed to use [: :-1] or reversed sir

Thomas Lotze Over a year ago

A simple solution without any slicing or built-ins: result = ''; for c in text: result = c + result

Martín Muñoz del Río · Accepted Answer · 2016-02-15 20:49:00Z

0

Strings are immutable, you have to create a new one.

Try:

def reverse(text):
    length = len(text)
    a = ''
    for pos in range(length):
        a += text[length-pos-1]
    print a

answered Feb 15, 2016 at 20:49

Martín Muñoz del Río

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Comments

Padraic Cunningham · Accepted Answer · 2016-02-15 20:58:11Z

0

As I commented strings as immutable and do not support assignment as a mutable structure like a list does, you can use a range starting from the length of the string -1 to 0 and concat each character to your a string:

def reverse(text):
    length = len(text) - 1
    a = ''
    for pos in range(length,-1,-1):
        a += text[pos]
    return a

answered Feb 15, 2016 at 20:58

Padraic Cunningham

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