How to use a reverse function in python3?

I want to reverse a string without slicing it but only using reverse function. So how can I use reverse function to reverse a string?

Girish
28 Sep
810 Views
4 Answers

MD

Meenal
28 Sep

With the improved support for Unicode in Python3, more and more folks will be working with languages (Arabic, Hebrew, etc.) that read right-to-left rather than left-to-right. So more and more folks will have a need to reverse a string. Unfortunately, Python doesn&rsquo;t have a built-in function, nor do string objects have a built-in method, to do what they will want.&nbsp; The obvious techniques don&rsquo;t work. This: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; try: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(1) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; s = &quot;a b c&quot; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; s = reverse(s) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(s) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; except Exception as e: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(e) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; try: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(2) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; s = &quot;a b c&quot; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; s = reversed(s) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(s) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; except Exception as e: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(e) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; try: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(3) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; s = &quot;a b c&quot; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; s.reverse() &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(s) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; except Exception as e: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(e) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; try: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(4) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; s = &quot;a b c&quot; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; s.reversed() &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(s) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; except Exception as e: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; print(e) produces this output 1 name &#39;reverse&#39; is not defined 2 &lt;reversed object at 0x00BAB5F0&gt; 3 &#39;str&#39; object has no attribute &#39;reverse&#39; 4 &#39;str&#39; object has no attribute &#39;reversed&#39; Fortunately, the solution is not too difficult. A little one-line function will do the trick. I call the function &ldquo;rev&rdquo; rather than &ldquo;reverse&rdquo; on the chance that Python will eventually acquire its own builtin function named &ldquo;reverse&rdquo;. def rev(s): return s[::-1]

Cancel

With the improved support for Unicode in Python3, more and more folks will be working with languages (Arabic, Hebrew, etc.) that read right-to-left rather than left-to-right. So more and more folks will have a need to reverse a string.
Unfortunately, Python doesn’t have a built-in function, nor do string objects have a built-in method, to do what they will want. The obvious techniques don’t work. This:
try: print(1) s = "a b c" s = reverse(s) print(s) except Exception as e: print(e) try: print(2) s = "a b c" s = reversed(s) print(s) except Exception as e: print(e) try: print(3) s = "a b c" s.reverse() print(s) except Exception as e: print(e) try: print(4) s = "a b c" s.reversed() print(s) except Exception as e: print(e)
produces this output
1 name 'reverse' is not defined 2 <reversed object at 0x00BAB5F0> 3 'str' object has no attribute 'reverse' 4 'str' object has no attribute 'reversed'
Fortunately, the solution is not too difficult. A little one-line function will do the trick.
I call the function “rev” rather than “reverse” on the chance that Python will eventually acquire its own builtin function named “reverse”.
def rev(s): return s[::-1]

0 Comments
Share

0

Other Related Discussions