Issue converting to string to integer.

[Fdama]

Hi,

I was following an exercise in a book when I edited the code and came across something I did not get. Here is the relevant part of the code that works:

start=None      #initialise  
while start !="":  
    start=input("\nStart: ")

    if start:
        start=int(start)
        finish=int(input("Finish: "))        

        print("word[",start,":",finish,"] is", word[start:finish])

I then changed the code to this:

start=None      #initialise  
while start !="":  
    start=int(input("\nStart: "))

    if start:
        
        finish=int(input("Finish: "))

        print("word[",start,":",finish,"] is", word[start:finish])

I combined the int conversion and the input on the same line, rather than to have two different statements. But  got an error message:

Traceback (most recent call last):
  File "C:\Users\Faisal\Documents\python\pizza_slicer.py", line 23, in <module>
    start=int(input("\nStart: "))
ValueError: invalid literal for int() with base 10: ''


Could someone tell me why I got this error message?

Thanks