随机密码生成器保持生成相同的密码

Question

I have to write a program that generates random passwords (using ASCII values and the chr() function) using Python and I have gotten my program to generate a random password, but when the program loops, it keeps printing the same random password and I have no idea what to do to fix it. If anyone could give me some advice, that would be great because I'm new to python

here is the code that I have so far:

import random, string

LNGTH=8
position=0
password=""
start=0
stop=0

while start==stop:
    input("would you like a password?")
    while position<LNGTH:
        x=random.randrange(9)
        character=chr(random.randrange(97, 97 + 26))
        choice=[str(x),character.upper(),character.lower()]
        pass_pos=random.choice(choice)
        password=password+pass_pos
        position+=1

    print(password)

Answer 1

You never reset position , so your while loop always returns True after the first password is generated.

Because you also do not reset password that means you generate just the one random password and re-display that value over and over again.

You need to reset both inside the outer while loop:

while start==stop:
    input("would you like a password?")
    position = 0
    password = ''

You could just use while True instead of start == stop there. You could also use a for loop instead of your inner while loop, simplifying your setup:

password = ''
for i in range(LNGTH):
    x=random.randrange(9)
    character=chr(random.randrange(97, 97 + 26))
    choice=[str(x),character.upper(),character.lower()]
    pass_pos=random.choice(choice)
    password=password+pass_pos

Cleaning that up some more by using string.ascii_letters and string.digits :

import string
import random

password_characters = string.ascii_letters + string.digits
length = 8

while True:
    if input("Would you like a password? ").lower() not in {'y', 'yes'}:
        break
    password = ''.join([random.choice(password_characters)
                        for _ in range(length)])
    print(password)

Answer 2

Once you have been through the loop once, position is equal to LNGTH , so the loop while position<LNGTH: will exit immediately.

Set position back to zero and password back to "" inside the outer loop

Answer 3

Your code only generates one password and keeps printing it. That's because it runs the loop while position < LNGTH just once: inside the loop, you increase the position until the password is long enough. But during next iterations, position will be already long enough - so the while loop won't be entered; instead, the already previously generated password will be printed.

You have to reset position to zero before entering the while loop.

Answer 4

At that point your program did everytime the same, so without initialising random you get everytime the same random. you should use random.seed() first or even better use random.SystemRandom() if available.