Beginning Python: Exceptions, Errors, and Warnings

Sometimes you may want Python to behave one way if there is an exception and another way if no error occurred. In this case, you will want to use a structure of try...except...else. To nuance the same previous example, we can add a third clause to affirm the user in not dividing by zero.

a = input("Please enter the dividend (the number to be divided):")
b = input("Please enter the divisor (the number by which to divide):")

try:
    print a/b
except (NameError, ZeroDivisionError), error:
    print "The divisor must not be zero. When the divisor is zero, Python hiccups like every good calculator should. The error passed was:"
    print "<div><b>%s</b><div>" %(error)
else:
    print "Not dividing by zero is a good thing."

Please enter the dividend (the number to be divided): 6
Please enter the divisor (the number by which to divide): 3
2
Not dividing by zero is a good thing.

Index: Beginning Python: Exceptions, Errors, and Warnings

1. What is an Exception?
2. Exception Exemplified
3. If at First You Don't Succeed
4. Try, Try Again
5. Taking Exception
6. If All Else Fails...
7. Raising Your Own Exceptions With raise - Part 1
8. Raising Your Own Exceptions With raise - Part 2