Finding the longest line from a text file consists of comparing the lengths of each line to determine which one is the longest. This can be done efficiently using various methods in Python. In this article, we will explore three different approaches to Finding the Longest Line from a Text File in Python.

Find the Longest Line from a Text File in Python

Below are the possible approaches to Finding the Longest Line from a Text File in Python.

• Using a for Loop and max with Key
• Using readlines Method
• Using List Comprehension and max

file.txt

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Find the Longest Line from a Text File Using a for Loop and max with Key

In this example, we are using the max function with the key parameter set to len to find the longest line in the file. The max function iterates through each line and compares their lengths.

with open('file.txt', 'r') as file:
    longest_line = max(file, key=len)

print("Longest line:", longest_line)

Output:

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Find the Longest Line from a Text File Using readlines Method

In this example, we are using the readlines method to read all lines into a list. We then iterate through the list to find the longest line by comparing the lengths of the lines.

with open('file.txt', 'r') as file:
    lines = file.readlines()
    longest_line = ""
    for line in lines:
        if len(line) > len(longest_line):
            longest_line = line

print("Longest line:", longest_line)

Output:

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Find the Longest Line from a Text File Using List Comprehension and max

In this example, we are using list comprehension to read all lines into a list and then applying the max function with the key parameter set to len. The max function identifies the longest line based on length.

with open('file.txt', 'r') as file:
    lines = [line for line in file]
    longest_line = max(lines, key=len)

print("Longest line:", longest_line)

Output:

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