Solution Exercise 25: python algorithm to reverse a given string

Mar 11, 2023

Exercise 25

Write a Python algorithm that asks the user to enter a word and return the opposite. Example: if the user enters the word 'python', the program returns 'nohtyp'.

Solution

```word = input("Enter a word: ")   # ask the user to enter a word
opposite = word[::-1]           # reverse the word using slicing
print("The opposite of", word, "is", opposite)   # print the opposite word
"""
output:
Enter a word: python
The opposite of python is nohtyp
"""```

Explanation:

1. input("Enter a word: "): asks the user to enter a word and stores it in the word variable.
2. word[: -1]: uses slicing to reverse the word. The [::-1] slice notation means to slice the entire string (:), with a step of -1, which reverses the order of the characters.
3. print("The opposite of", word, "is", opposite): prints the original word and its opposite.

Other method without slicing the word:

```# Ask user to enter a string s
s = input("Enter a string s : ")
# initialize the reverse of the string s to empty string
rev = ""

# Building the string s in a reversed way
for x in s:
rev = x + rev
print("The reverse of the string : '",s,"' is : ", rev)```

Younes Derfoufi
my-courses.net