Python: Reverse only the vowels of a given string

Last update on March 21 2025 12:42:17 (UTC/GMT +8 hours)

Reverse Vowels in String

Write a Python program to reverse only the vowels of a given string.

Sample Solution:

Python Code:

# Function to reverse the order of vowels in a string
def reverse_vowels(str1):
    vowels = ""  # Variable to store vowels in their original order
    for char in str1:
        if char in "aeiouAEIOU":  # Check if the character is a vowel
            vowels += char  # Append the vowel to the vowels variable
    result_string = ""  # Variable to store the result string with reversed vowels
    for char in str1:
        if char in "aeiouAEIOU":  # Check if the character is a vowel
            result_string += vowels[-1]  # Append the last vowel from the vowels variable
            vowels = vowels[:-1]  # Remove the last vowel from the vowels variable
        else:
            result_string += char  # Append non-vowel characters as they are
    return result_string

# Test cases
print(reverse_vowels("w3resource"))   
print(reverse_vowels("Python"))
print(reverse_vowels("Perl"))  
print(reverse_vowels("USA"))  

Sample Output:

w3resuorce
Python
Perl
ASU

Explanation:

Here is a breakdown of the above Python code:

• Define a function named "reverse_vowels()" that takes a string (str1) as input.
• Initialize an empty string (vowels) to store vowels in their original order.
• Iterate through each character in the input string. If the character is a vowel, append it to the 'vowels' variable.
• Initialize an empty string (result_string) to store the result string with reversed vowels.
• Iterate through each character in the input string. If the character is a vowel, append the last vowel from the vowels variable to the result string and remove it from the 'vowels' variable. If the character is not a vowel, append it to the result string.
• Return the final result string.
• Test the function with various input strings and print the results.

Visual Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to reverse only the vowels in a given string while keeping consonants in their original positions.
• Write a Python program to extract the vowels from a string, reverse them, and reinsert them into their original locations.
• Write a Python program to swap vowels from the beginning and end of a string using a two-pointer approach.
• Write a Python program to reverse the order of vowels in a string by collecting them and then replacing them sequentially.

Python Code Editor:

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