Generate alphanumeric strings sequentially

Question

I\'m trying to create a loop to generate and print strings as follows:

1. Alphanumeric characters only:
2. 0-9 are before A-Z, which are before a-z,

Answer 1

This seems like the simplest solution to me:

from string import digits, ascii_uppercase, ascii_lowercase

chars = digits + ascii_uppercase + ascii_lowercase
all_str = [''.join([a]) for a in chars] \
        + [''.join([a,b]) for a in chars for b in chars] \
        + [''.join([a,b,c]) for a in chars for b in chars for c in chars] \
        + [''.join([a,b,c,d]) for a in chars for b in chars for c in chars for d in chars]

print(all_str)
print("Number of strings:", len(all_str))

Example for strings with maximum 2 characters.

Of course, there may be a way to generalize to any max number of characters per string, but since you have a specific need for strings up to 4 characters, it's fine.