How can I read a text file into a string variable and strip newlines in Python?

Here’s how to read a text file into a string and remove newlines in Python, with multiple approaches and examples:

1. Basic Method (Read Entire File)

with open("file.txt", "r") as file:
    content = file.read().replace("\n", "").replace("\r", "")

print(content)

2. Handle All Line Endings with splitlines()

with open("file.txt", "r") as file:
    # splitlines() automatically handles \n, \r\n, and other line endings
    lines = file.read().splitlines()
    content = "".join(lines)

print(content)

3. Process Line-by-Line (Memory Efficient)

content = []
with open("file.txt", "r") as file:
    for line in file:
        # Remove newlines from each line
        content.append(line.rstrip("\r\n"))

result = "".join(content)
print(result)

4. Using List Comprehension

with open("file.txt", "r") as file:
    content = "".join([line.rstrip("\r\n") for line in file])

print(content)

5. Regex Approach (Advanced)

import re

with open("file.txt", "r") as file:
    content = re.sub(r"[\r\n]+", "", file.read())

print(content)

Key Differences

Method	Pros	Cons
replace()	Simple, explicit	Requires handling \n and \r separately
splitlines()	Handles all line endings automatically	Reads entire file at once
Line-by-line	Memory efficient for large files	More verbose
List Comprehension	Concise one-liner	Still loads all lines into memory
Regex	Flexible for complex patterns	Overkill for simple cases

Examples

Input File (file.txt):

Hello
World
This is a
test file

Output:

HelloWorldThis is atest file

Edge Case Handling

1. Mixed Line Endings (Windows + Unix):

   # Handles \r\n (Windows) and \n (Unix) in the same file
   with open("mixed.txt", "r") as file:
       content = "".join(line.rstrip("\r\n") for line in file)

2. Preserve Spaces:

   # Use rstrip() instead of strip() to keep leading spaces
   content = "".join(line.rstrip("\r\n") for line in file)

Performance Notes

• For small files: splitlines() or replace() are simplest
• For large files (>1GB): Use the line-by-line approach to avoid memory issues

Full Example with Error Handling

try:
    with open("file.txt", "r") as file:
        content = "".join(line.rstrip("\r\n") for line in file)
    print("Processed content:", content)
except FileNotFoundError:
    print("Error: File not found")
except Exception as e:
    print(f"An error occurred: {str(e)}")

Choose the method that best fits your use case! Let me know if you need further clarification.