Python Append Not Working

Question

So most of this code is my own, apologies for the fact it is probably a mess and/or horribly written, but my question is why the lines

D = open("C:\\aPATH\\hPROC.txt", "a")
D.write("End")

aren't appending "End" at the bottom of the file whenever it is called.

import time

def replace_all(text, rps):
    for i, j in rps.items():
        text = text.replace(i, j)
    return text

def replacer():
    inf = "hScrape.txt"
    ouf = "hPROC.txt"
    A = open(inf, "r")
    B = open(ouf, "w")
    reps = {"Result Date:":"", "Draw Result:":"", "Bonus":"", "January":"", "February":"", "March":"", "April":"", "May":"", "June":"", "July":"", "August":"", "September":"", "October":"", "November":"", "December":"", "With Max Millions!":"", "2009":"", "2010":"", "2011":"", "2012":"", "2013":"", "2014":"", "2015":"", "2016":"", "2017":"", "2018":"", "30th":"", "29th":"", "28th":"", "27th":"", "26th":"", "25th":"", "24th":"", "23rd":"", "22nd":"", "21st":"", "20th":"", "19th":"", "18th":"", "17th":"", "16th":"", "15th":"", "14th":"", "13th":"", "12th":"", "11th":"", "10th":"", "9th":"", "8th":"", "7th":"", "6th":"", "5th":"", "4th":"", "3rd":"", "2nd":"", "1st":"", "\t":""}
    txt = replace_all(A.read(), reps)
    B.write(txt)
    A.close
    B.close

    D = open("C:\\aPATH\\hPROC.txt", "a")
    D.write("End")

    C = open("C:\\aPATH\\Result.txt", "w+")
    print("Completed Filtering Sequence")
    time.sleep(3)


    while True:
        B = open("hPROC.txt", "r")
        z = B.readline()
        print(z)
        if "End" in z:
            C.write("DN")
            break
        else:
            if z != "\n":
                if " " not in z:
                    if int(z) < 10:
                        C.write("0" + z)
                    else:
                        C.write(z)

replacer()

you have forgotton to do a `D.close()` – Edwin van Mierlo Jan 31 '18 at 17:33 — Edwin van Mierlo, Jan 31 '18 at 17:33
@EdwinvanMierlo is the close going to affect it? – SoulFanatic Jan 31 '18 at 17:35 — SoulFanatic, Jan 31 '18 at 17:35

HunterM267 · Accepted Answer · 2018-01-31T17:45:13.673

1

Due to the way Python's file buffering system works, when opening a file and appending to it, but not closing it or flushing it, the appended lines aren't necessarily written.

See this for additional information on what flush does.

Therefore, a solution to your code would simply be changing it to

D = open("C:\\aPATH\\hPROC.txt", "a")
D.write("End")
D.close()

additionally, if you intend to append more and thus close the file later, you could make that snippet

D = open("C:\\aPATH\\hPROC.txt", "a")
D.write("End")
D.flush()

(which leaves the file open, and flushes the internal buffer to the OS buffer).

edited Jan 31 '18 at 17:45

answered Jan 31 '18 at 17:40

HunterM267

199
1
12

1

`D.flush()` by itself may not flush all data, merely flush the internal buffer to the os buffer – Edwin van Mierlo Jan 31 '18 at 17:43
@EdwinvanMierlo thank you; I’ve edited my post accordingly! – HunterM267 Jan 31 '18 at 17:45

score 0 · Answer 2 · answered Jan 31 '18 at 17:42

You have forgotten to close the file with D.close()

the close() will close the file, and writes all data which may be lingering in buffers.

If you do not want to close the file, you need to "flush" twice, example

D.flush()
os.fsync(D.fileno())

For the later, please do an import os, this will flush the os buffer for this file.

score 0 · Answer 3 · edited Feb 11 '22 at 15:26

0

The best method I found so far is as follows:

with open("your text file") as f:
    for line in f:
        if "your text to append" in line.rstrip('\r\n'):
           print("Exists!")
           break
    else:
        f.write("your text to append" + "\n")

edited Feb 11 '22 at 15:26

Dharman

30,962
25
85
135

answered Feb 11 '22 at 15:21

Eskias Yilma

1
1

Python Append Not Working

3 Answers3