readline loop commenting in an empty space Python

Question

The picture shows that everything else works properly instead there is an empty space in the code and that makes the program print "was invalid." I have no idea where the empty space comes from, any suggestions?

selec1 = open("strings.txt","r")
selec2 = "bob"
while selec2:
    selec2 = selec1.readline().replace("\n","")
    if selec2.isalnum() == True:
        print(selec2,"was ok.")
    if selec2.isalnum() == False:
        print(selec2,"was invalid.")

It looks like that the last line of the file is an empty line. Try to exclude that. — zanseb, Jun 06 '21 at 11:10

ti7 · Accepted Answer · 2021-06-06T11:27:17.920

I would do this iterating by-lines, which may be what's intended

For example

with open("strings.txt") as fh:  # close file when leaving scope
    for line in fh:              # file-likes are iterable by-lines
        line = line.strip()      # remove trailing newline
        print("{} was {}.".format(line, "ok" if line.isalnum() else "invalid"))

This does a few helpful things

using with open() instead of open() will close the file when you're done with it
calling .strip() on the line (as noted in comments) will remove trailing newline chars from lines more easily than replacing them
open() returns a file-like, which is already iterable by-lines (so you can simply write a structure like for x in y) and will omit a trailing final line
you can make a structure like "a" if something else "b" to simplify some flows

readline loop commenting in an empty space Python

1 Answers1