Finding 'n' Character Words in a Text File Python (original) (raw)

Last Updated : 12 Jan, 2026

Given a text file, the task is to find all words that are exactly ‘n’ characters long. This can be useful in text analysis, data cleaning, word filtering, or pattern-matching applications.

**Example: (Myfile.txt)

Hello, how are you? This is a simple text.

**Input: n=3
**Output: ['how', 'are', 'you']

Using Regular Expressions

Regular expressions allow you to match patterns in text efficiently. Here we can use \b\w{n}\b to find words of exact length n.

Python `

import re

fp = "Myfile.txt" n = 3

with open(fp, 'r') as f: text = f.read()

pattern = r'\b\w{' + str(n) + r'}\b' words = re.findall(pattern, text)

print(f"Words containing {n} characters:") print(words)

`

**Output:

['how', 'are', 'you']

**Explanation:

• **text = f.read(): Reads entire file content.
• **pattern = r'\b\w{n}\b': Matches words with exactly n characters (\b ensures word boundaries) (\w{n} ensure any word of length n)
• **re.findall(pattern, text): Returns a list of all matching words.

Using Split and List Comprehension

This method splits text into words and filters words based on length using list comprehension.

Python `

fp = "Myfile.txt" n = 3

with open(fp, 'r') as f: text = f.read()

w1 = text.split() w2 = [w for w in w1 if len(w) == n]

print(f"Words containing {n} characters:") print(w2)

`

**Output:

['how', 'are', 'you']

**Explanation:

• **text.split(): Splits the text into words.
• **[w for w in w1 if len(w) == n]: Filters words with length exactly n.

Using a Generator Function

Generators yield words one by one, making them memory-efficient for very large files.

Python `

fp = "Myfile.txt" n = 3

with open(fp, 'r') as f: for line in f: for w in line.split(): if len(w) == n: print(w)

`