Python @programming.dev EveryMuffinIsNowEncrypted @lemmy.blahaj.zone 2mo ago

Confused about multiplying floating-point & integer values

I'm currently doing Dr. Charles Severence's lessons on FreeCodeCamp to try to learn Python3. I'm on lesson exercise 02_03 and confused about multiplying floating-point and integer values.

The goal is to write a Python program multiplying hours worked by pay rate to come up with a pay quantity.

This is the code I wrote:

h = input("Enter hours: ")
r = input("Enter pay rate: ")
p = float(h) * r

I got a traceback error, and the video said the correct way to solve said error was change Line 3 from p = float(h) * r to p = float(h) * float(r).

However, what I'm confused about is why would I need to change r to a floating-point value when it's already a floating-point value (since it'd be a currency value like 5.00 or something once I typed it in per the input() command*?

What am I missing here?

*I can't remember: are the individual commands in a python line called "commands"?

Edit: Wrote plus signs in my post here instead of asterisks. Fixed.

EDIT: Thanks to @Labna@lemmy.world and @woop_woop@lemmy.world. I thought that the input() function was a string until the end-user types something in upon being prompted, and then becomes a floating-point value or integer value (or stays a string) according to what was typed.

This is incorrect: the value is a string regardless of what is typed unless it is then converted to another type.

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14 comments

I think I understand where you get confused. The returned value of the input function is always a string, you have to convert it into a number before using it in calculation. Otherwise the auto-parser will convert everything into string. Even if you use * or **.
- But I thought the "value" doesn't exist until the end-user types in the value, due to the use of input(). So it starts off as a string, then becomes whatever is typed in, which then gets filtered through the next line. So if I type 3, it'll be considered as an integer, and likewise as a float if I type 3.00.
  
  the signature for the input function (that's what it's called instead of command) is
  
  def input(__prompt: Any = ...) -> str
  
  which means it's always going to return a string.
  
  So it starts off as a string, then becomes whatever is typed in
  
  there's no real way for something to do that automatically without a much more robust setup.
  
  this snippet proves that
  
  test_int = input('enter integer:') print(type(test_int)) test_float = input('enter float:') print(type(test_float)) test_str = input('enter string:') print(type(test_str)) >> <class 'str'> >> <class 'str'> >> <class 'str'>
  
  it is the responsibility of your program to validate and do whatever you want with the result, and part of that can include casting it to a different type.
  
  Oh, I think I understand now.
  
  Thank you for clarifying that to me!
  
  No problem bud, good luck

14 comments