Python: Find the longest string of a list of strings

Last update on April 17 2025 13:03:10 (UTC/GMT +8 hours)

Longest String in List

Write a Python program to find the longest string in a given list of strings.

Input:
['cat', 'car', 'fear', 'center']
Output:
center

Input:
['cat', 'dog', 'shatter', 'donut', 'at', 'todo', '']
Output:
shatter

Visual Presentation:

Sample Solution-1:

Python Code:

# Define a function named 'test' that takes a list of strings 'words' as input
def test(words):
    # Use the max function to find the string with the maximum length in 'words' based on the key=len (length of each string)
    return max(words, key=len)

# Create a list of strings 'strs' with specific elements
strs = ['cat', 'car', 'fear', 'center']

# Print the original list of strings
print("Original strings:")
print(strs)

# Print a message indicating the operation to be performed on the list
print("Longest string of the said list of strings:")

# Print the result of the test function applied to the 'strs' list
print(test(strs))

# Create a different list of strings 'strs' with specific elements
strs = ['cat', 'dog', 'shatter', 'donut', 'at', 'todo', '']

# Print the original list of strings
print("\nOriginal strings:")
print(strs)

# Print a message indicating the operation to be performed on the list
print("Longest string of the said list of strings:")

# Print the result of the test function applied to the modified 'strs' list
print(test(strs))

Sample Output:

Original strings:
['cat', 'car', 'fear', 'center']
Longest string of the said list of strings:
center

Original strings:
['cat', 'dog', 'shatter', 'donut', 'at', 'todo', '']
Longest string of the said list of strings:
shatter

Flowchart:

Sample Solution-2:

Python Code:

# License: https://bit.ly/3oLErEI

# Define a function named 'test' that takes a list of strings 'words' as input
def test(words):
    # Define the lowercase and uppercase alphabet characters
    alphabet = "abcdefghijklmnopqrstuvwxyz"
    alphabet = alphabet + alphabet.upper()
    
    # Initialize an empty dictionary 'alphabet_dict' to store True for each alphabet character
    alphabet_dict = {}
    
    # Populate the 'alphabet_dict' with True for each alphabet character
    for k in alphabet:
        alphabet_dict[k] = True
    
    # Create a set 'alphabet_set' containing all alphabet characters
    alphabet_set = set(alphabet)
    
    # Initialize 'max_word' with the first word in the list
    max_word = words[0]
    
    # Iterate through each element 'el' in the list 'words'
    for el in words:
        # Check if 'el' contains only alphabet characters and is a subset of 'alphabet_set'
        # Also, check if it has the same set of characters as its intersection with 'alphabet_dict.keys()'
        if not ((set(el) <= alphabet_set) and (set(el) == set(el).intersection(alphabet_dict.keys()))):
            continue
        
        # Check if the length of 'el' is greater than or equal to the length of 'max_word'
        if len(el) >= len(max_word):
            # Update 'max_word' if the length condition is met
            max_word = el
    
    # Return the longest valid word
    return max_word

# Create a list of strings 'strs' with specific elements
strs = ['cat', 'car', 'fear', 'center']

# Print the original list of strings
print("Original strings:")
print(strs)

# Print a message indicating the operation to be performed on the list
print("Longest string of the said list of strings:")

# Print the result of the test function applied to the 'strs' list
print(test(strs))

# Create a different list of strings 'strs' with specific elements
strs = ['cat', 'dog', 'shatter', 'donut', 'at', 'todo', '']

# Print the original list of strings
print("\nOriginal strings:")
print(strs)

# Print a message indicating the operation to be performed on the list
print("Longest string of the said list of strings:")

# Print the result of the test function applied to the modified 'strs' list
print(test(strs))

Sample Output:

Original strings:
['cat', 'car', 'fear', 'center']
Longest string of the said list of strings:
center

Original strings:
['cat', 'dog', 'shatter', 'donut', 'at', 'todo', '']
Longest string of the said list of strings:
shatter

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to find and return the longest string from a list using the max() function with a custom key.
• Write a Python program to iterate through a list of strings and determine which has the maximum length.
• Write a Python program to sort a list of strings by length and output the last element as the longest string.
• Write a Python program to use recursion to compare string lengths in a list and return the longest string found.

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• Python Exercises Home ↩

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Python Code Editor :

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