Python Exercise: Checks whether a passed string is palindrome or not

Last update on April 22 2025 12:58:50 (UTC/GMT +8 hours)

12. Check if a String is a Palindrome

Write a Python function that checks whether a passed string is a palindrome or not.

Note: A palindrome is a word, phrase, or sequence that reads the same backward as forward, e.g., madam or nurses run.

Sample Solution:

Python Code:

# Define a function named 'isPalindrome' that checks if a string is a palindrome
def isPalindrome(string):
    # Initialize left and right pointers to check characters from the start and end of the string
    left_pos = 0
    right_pos = len(string) - 1
    
    # Loop until the pointers meet or cross each other
    while right_pos >= left_pos:
        # Check if the characters at the left and right positions are not equal
        if not string[left_pos] == string[right_pos]:
            # If characters don't match, return False (not a palindrome)
            return False
        
        # Move the left pointer to the right and the right pointer to the left to continue checking
        left_pos += 1
        right_pos -= 1
    
    # If the loop finishes without returning False, the string is a palindrome, so return True
    return True

# Print the result of checking if the string 'aza' is a palindrome by calling the 'isPalindrome' function
print(isPalindrome('aza')) 

Sample Output:

True 

Explanation:

In the exercise above the code defines a function named "isPalindrome()" that checks whether a given string is a palindrome (reads the same forwards and backwards). It uses two pointers (left_pos and right_pos) to traverse the string from both ends towards the middle, checking each character pair. Finally, it prints the result of checking whether the string 'aza' is a palindrome (which is True in this case).

Pictorial presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python function that checks if a string reads the same forwards and backwards using slicing.
• Write a Python function that iterates over a string from both ends simultaneously to determine if it is a palindrome.
• Write a Python function that ignores spaces and punctuation while checking if a sentence is a palindrome.
• Write a Python function that uses recursion to verify if a string is a palindrome.

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Python Code Editor:

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