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I'm having a problem using the int() function on a user input from the keyboard in Python 3 (latest version from website). The actual program will perform various numerical calculations, but I have written a short test program that shows the problem. The int() function works fine for values embedded in the code, but crashes if the same number/format is entered via the keyboard.

  1. dummy_num = (2.5) #just an example float number
  2. dummy_num = int(dummy_num) #converts 2.5 to integer 2
  3. print (f"{dummy_num}") #verifies result of "2"
  4. variable_test = input ("type 2.5 please:")
  5. print (f"{variable_test}") #verifies 2.5 is actually entered
  6. variable_test = int(variable_test)

The program runs as expected for lines 1 to 5. If 2.5 is entered via the keyboard in line 4, line 5 prints 2.5, but then line 6 crashes the program. An error message is generated as follows: variable_test = int(variable_test) ValueError: invalid literal for int() with base 10: '2.5'

I don't understand why the int() function works fine for the value "2.5" in line 2, but crashes in line 6 - even though line 5 shows that the number entered is indeed 2.5 and the same program instruction works fine in line 2.

Sorry if this is a newbie error, but I have run out of ideas. Note that I put a few #comments in the above code just for the purpose of this question.

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It's not an Apple question. Nevertheless it's always good idea to use Python built-in help:

>>> help(int)
Help on class int in module builtins:

class int(object)
 |  int([x]) -> integer
 |  int(x, base=10) -> integer
 |
 |  Convert a number or string to an integer, or return 0 if no arguments
 |  are given.  If x is a number, return x.__int__().  For floating-point
 |  numbers, this truncates towards zero.
 |
 |  If x is not a number or if base is given, then x must be a string,
 |  bytes, or bytearray instance representing an integer literal in the
 |  given base.  The literal can be preceded by '+' or '-' and be surrounded
 |  by whitespace.  The base defaults to 10.  Valid bases are 0 and 2-36.
 |  Base 0 means to interpret the base from the string as an integer literal.
/.../

To pinpoint: If x is not a number or if base is given, then x must be a string, bytes, or bytearray instance representing an integer literal in the given base

Simple test:

>>> int("2.5")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '2.5'
>>> int("2")
2

Line #2 float is converted into int, on line #6 string 2.5 (which doesn't represent integral literal) is attempted to convert.

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