Python Password Generator

Question

I am trying to create a password generator in Python that must contain an uppercase letter, lowercase letter, and a number, and must have a length between 6 and 20 characters.

   import random
   import string
   def password_gen():
        while True:
            length = random.randint(6,20)
            pwd = []
            for i in range(length):
                prob = random.random()
                if prob < 0.34:
                    char = random.choice(string.ascii_lowercase)
                    pwd.append(char)
                elif prob < 0.67:
                    char = random.choice(string.ascii_uppercase)
                    pwd.append(char)
                else:
                    char = str(random.randint(0,9))
                    pwd.append(char)
            pwd = ''.join(pwd)
            #check password here
            return pwd

However, I am having trouble checking the password to make sure it contains the required characters listed earlier. I am not sure if/how i would use a continue statement.Any help would be greatly appreciated!

Answer 1

I think this would be a bit easier to ensure you meet the base requirements if you just handle those upfront.

import random
import string

def generate_pw():
    length = random.randint(6,20) - 3
    pwd = []
    pwd.append(random.choice(string.ascii_lowercase))
    pwd.append(random.choice(string.ascii_uppercase))
    pwd.append(str(random.randint(0,9)))
    # fill out the rest of the characters
    # using whatever algorithm you want
    # for the next "length" characters
    random.shuffle(pwd)
    return ''.join(pwd)

This will ensure your password has the characters you need. For the rest of the characters you could for example just use a list of all alphanumeric characters and call random.choice length times.