How do I stop the program from crashing when given a letter in the place of a number?

Question

employee = float(raw_input('Employee code number or 0 for guest:') or 0.0)

if employee == isalpha:
    print "Nice try buddy"
    print "Welcome BIG_OLD_BUDDY"

This code does not recognize alphabetical input.

That's because you're immediately parsing it as a float. Don't cast a raw value, make it *can* be cast first, probably with a try:except block — Sterling Archer, Aug 09 '17 at 03:25
`employee = raw_input('Employee code number or 0 for guest:')`;`if employee.isdigit(): employee = int(employee) else: something else...` — Alexander, Aug 09 '17 at 03:31

score 1 · Answer 1 · edited Aug 10 '17 at 12:55

1

There are 2 ways.

You can catch the the exceptions and pass.

try:
    employee = float(raw_input('Employee code number or 0 for guest: ') or 0.0)
except KnownException:
    #  You can handle Known exception here.
    pass
except Exception, e:
    # notify user
    print str(e)

Check for the type of input and then do what you want to do.

employee = raw_input('Employee code number or 0 for guest:')

if(employee.isalpha()):
    print "Nice try buddy"
    print "Welcome BIG_OLD_BUDDY"
else:
    print "Your employee no is:" + str(employee)

Do not use try and catch until and unless there are chances of unknown exceptions. To handle things with if and else are recommended.

Read more about : why not to use exceptions as regular flow of control

edited Aug 10 '17 at 12:55

yt.

31
7

answered Aug 09 '17 at 03:43

Ujjaval Moradiya

212
1
12

Try to avoid option 1 unless there is a practical reason for it. – Jerrybibo Aug 09 '17 at 04:26
This error is returned File "C:\Users\gavin.whitfort\Desktop\2017 Work\Software Devolpment\SAT\POS Solution.py", line 117, in program if(employee.isAlpha()): AttributeError: 'str' object has no attribute 'isAlpha' >>> – GAVDADDY Aug 09 '17 at 23:55
1

Right method to check for the alpha is isalpha(). You should do some research on your man. – Ujjaval Moradiya Aug 10 '17 at 04:01
@Jerrybibo is right, one should avoid try and catch. – Ujjaval Moradiya Aug 10 '17 at 04:03

score 0 · Answer 2 · answered Aug 09 '17 at 03:25

0

Use a try

try:
    employee = float(raw_input('Employee code number or 0 for guest: ') or 0.0)
except ValueError:
    print "Nice try buddy"
    print "Welcome BIG_OLD_BUDDY"

answered Aug 09 '17 at 03:25

SomeGuyOnAComputer

3,408
3
27
52

score 0 · Answer 3 · answered Aug 09 '17 at 03:30

You can use try/except as the other answer suggested, and if you want to use str.isalpha() you have to call it on the string, not compare it with the string. For example:

employee = raw_input('Employee code number or 0 for guest:')

if employee.isalpha():
    print "Nice try buddy"
    print "Welcome BIG_OLD_BUDDY" 
else:
    employee = float(employee)

score 0 · Answer 4 · answered Aug 10 '17 at 12:58

If you want it to only accept positive integers you can check usingisdigit() which is basically the opposite of isalpha().Try:

    employee = raw_input('Employee code number or 0 for guest:')

    if employee.isdigit()==False:
      print "Nice try buddy"
      print "Welcome BIG_OLD_BUDDY"
    elif int(employee)==0:
      print "You are a guest"
    else:
      print "Your employee no is:" ,employee

I also added a bit of code using elif to check if you're a guest

How do I stop the program from crashing when given a letter in the place of a number?

4 Answers4