Python: True if variable is integer or float

Question

I am trying to write a small program from a book assignment, but I am having trouble with detecting if the user's input is a int/float (increment to the total) or string (return error). I tried using .isdigit() on the add_to_total variable but when I type in a float, it skips straight to the else code block. I have tried searching on the internet but can't find a clear answer. Here is my code:

total = 0
print("Welcome to the receipt program!")

while True:
    add_to_total = raw_input("Enter the value for the seat ['q' to quit]: ")
    if add_to_total == 'q':
        print("*****")
        print "Total: $%s" % total
        break
    if add_to_total.isdigit(): #Don't know how to detect if variable is int or float at the same time.
        add_to_total = float(add_to_total)
        total += add_to_total
    else:
        print "I'm sorry, but '%s' isn't valid. Please try again." % add_to_total

Any answer would be greatly appreciated.

score 5 · Answer 1 · answered May 01 '14 at 11:22

You can always use the try... except approach:

try:
    add_to_total = float(add_to_total)
except ValueError:
    print "I'm sorry, but '%s' isn't valid. Please try again." % add_to_total
else:
    total += add_to_total

Remember: it's easier to ask forgiveness than permission

Daniel · Accepted Answer · 2014-05-01T11:41:08.780

4

Use exceptions to catch user inputs that can not be summed up. Switch from testing any user input, to just guard the mathematical operation to sum up receipts.

total = 0
print("Welcome to the receipt program!")

while True:
    add_to_total = raw_input("Enter the value for the seat ['q' to quit]: ")
    if add_to_total == 'q':
        break
    try:
        total += float(add_to_total)
    except ValueError:
        print "I'm sorry, but '%s' isn't valid. Please try again." % add_to_total
print("*****")
print "Total: $%s" % total

edited May 01 '14 at 11:41

answered May 01 '14 at 11:21

Daniel

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thank you, it worked. I think i tried using this method before but put it somewhere wrong. Accepted answer. – Thomas May 01 '14 at 11:27

score 4 · Answer 3 · edited May 23 '17 at 11:50

4

Very close to an old entry : How can I check if my python object is a number?. The answer is:

isinstance(x, (int, long, float, complex))

edited May 23 '17 at 11:50

Community

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answered May 01 '14 at 11:22

user3585718

396
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4

The OP is checking if a string can be converted to an number, not if an an existing object has a numeric type. – chepner May 01 '14 at 11:31

Python: True if variable is integer or float

3 Answers3