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Python Reverse String

Reverse the characters in a string. Use list comprehension, reverse and the join method.

Reverse string. Programs sometimes have unusual requirements. For example we might need to reverse the characters in a string. This could help for generating a unique key from some data.Strings

With list comprehension, we get the characters of a string. And then we can reverse those characters with reverse() and call join() to join them back again.

Example def. Here we introduce a reverse_string method. This method receives a string and returns a reversed form of it. We first use list comprehension to get a character list.

Tip: With a list of characters, returned by the list comprehension, we can manipulate the ordering of the characters.

Reverse: We invoke the list's reverse() method on the characters list. This changes the order of the letters in-place.

Join: We join the characters together on an empty delimiter. This concatenates the chars into a new, reversed string.

Python program that implements string reverse method def reverse_string(value): # Get characters from the string. characters = [c for c in value] # Reverse list of characters. characters.reverse() # Join characters back into string with empty delimiter. return "".join(characters) # Test our string reversal method. test1 = "cat" reversed1 = reverse_string(test1) print(test1) print(reversed1) test2 = "abcde" reversed2 = reverse_string(test2) print(test2) print(reversed2) Output cat tac abcde edcba

Some concepts. Lists are powerful in Python. We can reverse them. With a list comprehension, meanwhile, we can quickly construct a list of characters from an expression.ListList Comprehension

So: The trick to manipulating strings is to convert them to lists first. We then just manipulate the list elements.

A review. By reversing strings, we learn how to manipulate strings in many ways. We can change the individual characters, or reorder the characters in any fashion. This is powerful.
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