How to check if string has lowercase letter, uppercase letter and number [duplicate]

Answer 1

You have some problems with your checking logic. First of all you re-set your control variables before the while condition could check them. Furthermore you used and to test if all conditions are true, while or is what you should be using. If you want to keep the basic structure of your code, the best way to go is to use only True in your while statement and then break the loop once all conditions are fulfilled. Of course, as shown in the other answers, there are much more compact ways to check that all conditions are fulfilled.

passwd = raw_input("enter your password: ")
upper = 0
lower = 0 
number = 0
while True:
    for x in passwd:
        if x.isupper()==True:
            print 'upper'
            upper+=1
        elif x.islower()==True:
            print 'lower'
            lower+=1
        elif x.isalpha()==False:
            print 'num'
            number+=1
    if len(passwd) < 7 or upper <= 0 or lower <= 0 or number <= 0:
        print ('password not complex enough')
        passwd = raw_input('please enter password again ')
        upper = 0
        lower = 0
        number = 0
    else:
        break



print 'final password:', passwd

Output:

enter your password: pA
lower
upper
password not complex enough
please enter password again pA1ghlfx78
lower
upper
num
lower
lower
lower
lower
lower
num
num
final password: pA1ghlfx78

Answer 2

If a password must consist of ASCII letters and numbers only, then the most efficient approach would be to use sets:

from string import ascii_lowercase, ascii_uppercase, digits

def is_valid(password):
    if len(password) < 7:
        return False
    password_set = set(password)
    return not any(password_set.isdisjoint(x)
                   for x in (ascii_lowercase, ascii_uppercase, digits))

If unicode characters are allowed, you could use any():

 def is_valid(password):
     return (len(password) >= 7 and
             any(c.islower() for c in password) and
             any(c.isupper() for c in password) and
             any(c.isdigit() for c in password))

Answer 3

May this is helpful for you.I use sum(1 for c in the string if c.islower()) to find the total number of lowercase. and same way to find the total number of uppercase and digit.len(string) to find length of string.

string=input()
if ((sum(1 for c in string if c.islower())>=1) and (sum(1 for c in string if 
c.isupper())>=1) and (sum(1 for c in string if c.isdigit())>=1) and (len(string)>=7)):
    print("Password is complex")
else:
    print ("Password not complex enough")

Answer 4

You can simplify the whole logic by utilising unicodedata.category to collect what category of a character is and then check to see if all expected are present, eg:

import unicodedata

is_valid = (
    len(password) >= 7 and 
    {'Ll', 'Lu', 'Nd'}.issubset(unicodedata.category(ch) for ch in password)
)