readline() code in my python app works not correctly. Why?

Question

I am building an app by python3.8.3 and pyqt5. This is a part of my code:

def logupd(self):
        users=open('NeveshtarUsers.txt', 'w')
        users.write('Username: ')
        users.write(self.user2.text())
        users.write(' Password: ')
        users.write(self.pass2.text())
        users.write('.\n')
        users.write('Name: ')
        users.write(self.name.text())
        users.write('.\n')
        users.write('....................\n')
        self.no.setText('Loggind up has succesed. Please Login')

        with open('NeveshtarUsers.txt') as file:
            print('salam')
            data = file.readlines()
            print(data)

When I call this code, the output is:

salam
[]

Why data is empty? What's the problem?

Have you checked wheter the lines have been written to the file? If the file remains empty, then file.readlines() will return an empty list. — Wu Wei, May 31 '20 at 07:32

score 1 · Accepted Answer · answered May 31 '20 at 04:37

I think the problem is not closing the file that is open in write mode

def logupd(self):
        users=open('NeveshtarUsers.txt', 'w')
        users.write('Username: ')
        users.write(self.user2.text())
        users.write(' Password: ')
        users.write(self.pass2.text())
        users.write('.\n')
        users.write('Name: ')
        users.write(self.name.text())
        users.write('.\n')
        users.write('....................\n')
        self.no.setText('Loggind up has succesed. Please Login')
        # close the file that is opened in write , the text will get updated to the system's memory 
        # only when the file is closed 
        users.close()
        with open('NeveshtarUsers.txt') as file:
            print('salam')
            data = file.readlines()
            print(data)

readline() code in my python app works not correctly. Why?

1 Answers1