字符串索引超出python范围？

Question

I am making a security login program in python, and I keep getting this error message: IndexError: string index out of range.

The error is for the line character=password[c] . I am at the part where it checks if the password that the user enters has a number. If it does not have a number, the password is invalid. How do I fix this?

while c<numbercharacters:
    character=password[c] 
    c=c+1
    while character!="1" and character!="2" and character!="3" and character!="4" and character!="5" and character!="6" and character!="7" and character!="8" and character!="9" and character!=0: #checking if password has a number
        print "This password is not valid, it does not contain a number. Please create another." 
        password= raw_input ()
        numbercharacters=len(password) 
        character=password[c] 

c is the variable for the counter.

Answer 1

When you get fresh input for the password, due to it being invalid, you don't reset your counter c to zero to start the checking process from scratch again.

# After this block
password= raw_input ()
numbercharacters=len(password) 
# Reset your counter to zero
c = 0
character=password[c]

You can also simply for your character check for digits with either

while not character.isdigit():
# or 
while character not in '0123456789':

Answer 2

If you want to check if there is a number you can just do

password= raw_input ()
if not any(character.isdigit() for character in password):
    print "This password is not valid, it does not contain a number. Please create another." 

If you want to re-ask for a password until it has a number

 password= raw_input ()
 if not any(character.isdigit() for character in password):
    while not any(character.isdigit() for character in password):
        print "This password is not valid, it does not contain a number. Please create another." 
        password= raw_input ()