How Can I Efficiently Search and Replace Text in a File Using Python 3?

Search and Replace Text in a File with Python 3

In Python 3, you can search for and replace text in a file using various methods. One common approach is illustrated in the provided code.

Code Analysis

Your provided code reads the text to find and replace as well as the file path from the user. It then opens the file for reading and writing, searches for occurrences of the search text using fileinput, replaces it with the replacement text, and writes the modified content to the file.

Issue with Replacing 'abcd' by 'ram'

The reported issue with replacement results occurs because the string 'abcd' is longer than 'ram'. When 'abcd' is replaced by 'ram', the extra characters at the end of the replaced text are not removed, resulting in the "junk characters" you observed.

Solution

To resolve this issue, you should account for the potential difference in length between the search and replacement strings. Here's an updated version of the code that should work correctly:

import os
import fileinput

print("Text to search for:")
textToSearch = input("> ")

print("Text to replace it with:")
textToReplace = input("> ")

print("File to perform Search-Replace on:")
fileToSearch = input("> ")

tempFile = open(fileToSearch, 'r+')

for line in fileinput.input(fileToSearch):
    if textToSearch in line:
        tempFile.write(line.replace(textToSearch, textToReplace))
    else:
        tempFile.write(line)

tempFile.close()

input('Press Enter to exit...')

Updated Implementation

Instead of replacing all occurrences of textToSearch with textToReplace, the updated code uses line.replace() within the loop, ensuring that only the specific found occurrence is replaced. This modification eliminates the residual junk characters.

Memory-Efficient Solution

The code assumes that the file fits entirely into memory. If the file is too large, consider reading and writing to the file in chunks to avoid memory issues.

The above is the detailed content of How Can I Efficiently Search and Replace Text in a File Using Python 3?. For more information, please follow other related articles on the PHP Chinese website!