Python.. Pickle issue

[MyrinNew]

I JUST WANNA KNOW WHY THAT UNPICKLING ERROR RAISES. BUT NOT IN PREVIOUS CASES

Program:

import pickle


def create():

fo = open("binary.dat", "wb")

count = int(input("Enter number of records: "))

for i in range(count):

roll = int(input("Enter roll no: "))

name = input("Enter name: ")

class_name = input("Enter class: ")

data = [roll, name, class_name]

pickle.dump(data, fo)

fo.close()


def check():

fo = open("binary.dat","rb+")

search = int(input("Enter roll.no to search: "))

name = input("Enter name to update: ")

try:

while True:

rpos = fo.tell()

data = pickle.load(fo)

if data[0] ==search:

data[1] = name

fo.seek(rpos)

pickle.dump(data, fo)

#fo.truncate()




except EOFError:
fo.close()





def readall():

with open("binary.dat", "rb") as fo:

try:

while True:

data = pickle.load(fo)

print(data)

except EOFError:

pass


create()

readall()

check()

readall()


output:


rvd@betaceti:~/Projects$ /home/rvd/Projects/.venv/bin/python /home/rvd/Projects/POCs/class.py

Enter number of records: 2

Enter roll no: 1

Enter name: er

Enter class: 12

Enter roll no: 2

Enter name: we

Enter class: 12

[1, 'er', '12']

[2, 'we', '12']

Enter roll.no to search: 1

Enter name to update: kjsn

[1, 'kjsn', '12']

[2, 'we', '12']

rvd@betaceti:~/Projects$ /home/rvd/Projects/.venv/bin/python /home/rvd/Projects/POCs/class.py

Enter number of records: 1

Enter roll no: 1

Enter name: s

Enter class: 12

[1, 's', '12']

Enter roll.no to search: 1

Enter name to update: zdrtgh

[1, 'zdrtgh', '12']

rvd@betaceti:~/Projects$ /home/rvd/Projects/.venv/bin/python /home/rvd/Projects/POCs/class.py

Enter number of records: 2

Enter roll no: 1

Enter name: s

Enter class: 12

Enter roll no: 2

Enter name: er

Enter class: 12

[1, 's', '12']

[2, 'er', '12']

Enter roll.no to search: 1

Enter name to update: dfrgdr

Traceback (most recent call last):

File "/home/rvd/Projects/POCs/class.py", line 42, in

check()

File "/home/rvd/Projects/POCs/class.py", line 21, in check

data = pickle.load(fo)

^^^^^^^^^^^^^^^

_pickle.UnpicklingError: invalid load key, '\x00'.




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