Change text in file with Python

Question

def false_to_true():
    name = input(\"Input name: \")
    file=open(\"users.txt\",\"r\")
    lines = file.readlines()
    file.close()
    for line in lines:
              


        

Answer 1

Ask for name and iterate throw your lines to check for username, like this:

def false_to_true():
    name = input("Input name: ")
    file=open("users.txt","r")
    lines = file.readlines()
    file.close()

    users = open("users.txt", "w")
    for line in lines:
    username, lel, type = line.split("/")
    if name == username:
        type = 'True\n'# \n for new line type ends with '\n'
    users.write("/".join([username, lel, type]))
    users.close()
false_to_true()

Answer 2

You can just use the csv library and forget about string manipulation:

import csv

def false_to_true():
    #read from user.txt file into list(data)
    with open('users.txt', 'r') as userfile:
        data = [row for row in csv.reader(userfile,
                                          delimiter="/",
                                          quoting=csv.QUOTE_NONE)]
    while True:
        #waiting for input until you enter nothing and hit return
        username = input("input name: ")
        if len(username) == 0:
            break
        #look for match in the data list
        for row in data:
            if username in row:
                #change false to true
                row[2] = True
                #assuming each username is uniqe break out this for loop
                break

    #write all the changes back to user.txt
    with open('users.txt', 'w', newline='\n') as userfile:
        dataWriter = csv.writer(userfile,
                                delimiter="/",
                                quoting=csv.QUOTE_NONE)
        for row in data:
            dataWriter.writerow(row)


if __name__ == '__main__':
    false_to_true()

Answer 3

To modify a text file inplace, you could use fileinput module:

#!/usr/bin/env python3
import fileinput

username = input('Enter username: ').strip()
with fileinput.FileInput("users.txt", inplace=True, backup='.bak') as file:
    for line in file:
        if line.startswith(username + "/"):            
            line = line.replace("/False", "/True") 
        print(line, end='')

See How to search and replace text in a file using Python?

Answer 4

Open the input and output files, make a set out of the user-input names (terminated by a blank line), then create a generator for strings of the proper format that check for membership in the user-input names, then write these lines to the output file:

with open('names.txt') as f, open('result.txt', 'w') as out:
    names = {name for name in iter(input, '')}
    f = ('{}/{}/{}'.format(a,b,'True\n' if a in names else c) for a,b,c in (line.split('/') for line in f))
    output.writelines(f)