ValueError：以10为底的int（）的无效文字：''

Question

I'm new in Python 3 and need some help, my error is:

"ValueError: invalid literal for int() with base 10: ''  " 

any ideas? The code I'm using is the following:

liste = [1, 2, 3]

def liste_pop():
    print(liste)
    pop = int(input('remove = Enter um das letzte Element der Liste auszugeben + entfernen oder die Position eingeben'))
    liste.pop(pop)
    return

Answer 1

You did not enter a number during input, instead you simply pressed enter (and got back the empty string). You need to add code to handle the situation where a user enters invalid input , in Python, this is performed with a try-except where you specify the error you're expecting ValueError in the except clause:

def liste_pop():
    print(liste)
    while True:
        try:
            pop = int(input('remove = Enter um das letzte Element der Liste auszugeben + entfernen oder die Position eingeben'))
            break
        except ValueError as e:
            print("Only numbers accepted")
    liste.pop(pop)

Of course, this has an additional issue, what if a user enters a number outside the accepted range? An IndexError is raised; you'll need another try-except for that (I'll let you handle it on your own.)