Try statement - multiple conditions - Python 2

Question

I have little problem with try statement along with multiple conditions. When there is error at 2nd condition, it asks for 1st condition. What I want from it to do is to repeat the same condition, not the whole cycle. I hope you understand me, since my English isn't very good and also I'm newbie to Python so I also don't know how to describe it in my native language.

I hope the following example will help you to better understand my thought.

while True:
    try:
        zacatek = float(raw_input("Zacatek: "))
        konec = float(raw_input("Konec: "))
    except Exception:
        pass
    else:
        break

it does following:

Zacatek: 1
Konec: a
Zacatek:

but I want it to do this:

Zacatek: 1
Konec: a
Konec:

Thanks in advance for any help.

Sven Marnach · Accepted Answer · 2011-11-13 17:19:59Z

5

Write a function to query for a single float, and call it twice:

def input_float(msg):
    while True:
        try:
            return float(raw_input(msg))
        except ValueError:
            pass
zacatek = input_float("Zacatek: ")
konec = input_float("Konec: ")

answered Nov 13, 2011 at 17:19

Sven Marnach

608k123 gold badges969 silver badges866 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

bigendian · Accepted Answer · 2011-11-13 17:25:01Z

0

What's happening is that your except clause is catching a ValueError exception on your answer to Konec and returning to the top of the loop.

Your float function is trying to cast a non-numeric response "a" to a float and it throwing the exception.

answered Nov 13, 2011 at 17:25

bigendian

8186 silver badges11 bronze badges

Comments

Óscar López · Accepted Answer · 2011-11-13 17:31:36Z

0

Alternatively, you could write a different loop for each input:

zacatek = None
while not zacatek:
    try:
        zacatek = float(raw_input("Zacatek: "))
    except Exception:
        continue

konec = None
while not konec:
    try:
        konec = float(raw_input("Konec: "))
    except Exception:
        continue

answered Nov 13, 2011 at 17:31

Óscar López

237k38 gold badges321 silver badges391 bronze badges

1 Comment

Sven Marnach Over a year ago

@delnan: No, it isn't. This version will ask again if I enter '0', mine doesn't.

Collectives™ on Stack Overflow

Try statement - multiple conditions - Python 2

3 Answers 3

Comments

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related