I can't understand this block

Python Help
1

Ey guys I’m learning pythoin using w3school actually my experience it’s beginner. I’m prcaticing with the try: except: block and I can’t resolve this:

 def manejoErrores(valor):
    try:
        valor = float(valor)
    except:
        print("error")
    return calcular(valor)

def mensaje():
    income = input("Ingrese el monto total: ")
    return manejoErrores(valor)

x = mensaje()
print(x)

It’s suppose that code recive a amount from a invoice, originally is a string and I try to convert in a float yo continue when I insert number as the beginning the block works but when I insert string to prove the function and try to insert values again it doesn’t work

2

In your original function, try updating to:

def mensaje():
    valor = input("Ingrese el monto total: ")
    return manejoErrores(valor)

By the way, where is the function calcular defined from the first function? Anytime that you use a variable or a function, or any object for that matter must either first be assigned or defined. Here, calcular is not defined so you will still be getting an error.

3

Exactly what happens when you try the code?

Exactly what do you think should happen instead, and how is that different?

4

There are a few things to comment on in this code. Taking your mensaje
function first:

 def mensaje():
     income = input("Ingrese el monto total: ")
     return manejoErrores(valor)

This calls manejoErrores(valor) but does not set a value for valor.
And the value in income, which came from input(), is not used. I
suspect you should be passing income to the manejoErrores()
function.

 def manejoErrores(valor):
     try:
         valor = float(valor)
     except:
         print("error")
     return calcular(valor)

What should the return value of this function be? For valid values of
valor I imagine it should be calcular(valor). But what should happen
when valor is not a valid “float string”?

Presently this just prints "error". But then execution falls through
and runs the return statement anyway, which doubtless raises its own
exception because valur if still a string.

Also, try to always avoid a “bare except”, this line:

 except:

This catches any exception. For example, if you type a variable name
wroing Python will raise a NameError exception and your code will also
catch that. Catch only what you expect to handle: to accomodate in
some way. So for float() with a bad number string you should expect a
ValueError, and only catch that:

 except ValueError:

Cheers,
Cameron Simpson cs@cskk.id.au

5

Hey guys, I’m appreciate your answer I just wanted to encapsulate everything in functions to manage the messages to the user and los procesos. it’s just a practice, and this morning I’ve started everything and in the function mensaje() I did the comprobations I like to separate both process because my original idea was drive messages and comprobations in different process,

The final code its:


"""practice #5"""


def calculateinvoice(fvalue):
    """function to receive the real value and 
       return final values"""
    return fvalue


def message():
    """function to receive the invoice's value and 
       validate for errors
    """
    err = True
    while err:
        try:
            value = float(
                input("Enter the total of your invoice: "))
            err = False
        except ValueError:
            print("Enter correct values,")

    return value


vvalue = message()
nvalue = calculateinvoice(vvalue)
print(nvalue)

It’s deffinetly not the best code I’d like to do a function for process if there are something to improve let me know. Thank you Guys!