Consider the following code below. I was told that if regExMagic() doesn’t find a match for Lucy in the string of text, it returns “None” to regExMagic(). Since “None” is already a string why do we still need to wrap regExMagic() in a str() in the comparison below?
What’s interesting is when I removed str() it executed only the else statement (not seen here) for each line (image below) and it didn’t throw any TypeError exception that I’m trying to compare 2 different types assuming an int could have been returned to regExMagic(). But since only the else got executed then it probably didn’t even bother throwing an exception?
So my main question is why do we need to include str() in this case even though “None” gets returned as I was told to regExMagic()?
Am I missing something here?
import re def regExMagic(pattern, string): objectMatch = re.search(pattern, string) return objectMatch def readingLinesWithRegEx(): try: with open('people.txt') as file_object: contents = file_object.readlines() for line in contents: pattern = 'HEllo$' if str(regExMagic(pattern, line)) == "None": print(line)
It returns the value
None (whose type is
NoneType), not the string
"None". So if you want to compare it with a string you have to convert it.
But it’s simpler to just compare it directly without converting:
if regExMagic(pattern, line) is None: print(line)
You can also just test the truth value, since any other value it returns will be a non-falsey object. So just write:
if not regExMagic(pattern, line): print(line)