Chapter 13: Managing Errors & Exceptions

example 13.1, page no. 231

"""
there is no need of semicolon. We will show error for something else
"""

print "Hello Python..."

Hello Python...

example 13.2, page no. 232

a = 10
b = 5
c = 5
x = a/(b-c) #It will show ZeroDivisionError
print "x = ", x
y = a/(b+c)
print "y = ", y

---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)
<ipython-input-5-9289236a4a07> in <module>()
      3 b = 5
      4 c = 5
----> 5 x = a/(b-c)
      6 print "x = ", x
      7 y = a/(b+c)

ZeroDivisionError: division by zero

Example 13.3 page no : 235

a = 10
b = 5
c = 5
try:
    x = a/(b-c)
except Exception,e :
    print "Division by zero"
y = a/(b+c)
print "y = ",y

Division by zero
y =  1

Example 13.4 page no : 236

import sys
invalid = 0
count = 0
for i in sys.argv:
    try:
        a = int(i)
    except:
        invalid += 1
        print "Invalid number" , i
        continue
    count += 1

print "Valid Numbers : " ,count
print "Invalid numbers ",invalid
        

 Invalid number -c
Invalid number -f
Invalid number /tmp/tmp1tOqar/profile_default/security/kernel-082ebfe6-5650-4ba4-8bcf-cd17bc99af7a.json
Invalid number --IPKernelApp.parent_appname='ipython-notebook'
Invalid number --profile-dir
Invalid number /tmp/tmp1tOqar/profile_default
Invalid number --parent=1
Valid Numbers :  0
Invalid numbers  7

example 13.5, page no. 239

a = [5,10]
b = 5
try:
    x = a[2]/b - a[1]
except AssertionError:
    print "AssertionError:"
except IndexError:
    print "Array Index Error"
except Exception:
    print "Any Error"
y = a[1]/a[0]
print "y = " , y 

Array Index Error
y =  2

Example 13.6 page no : 239

x = 5
y = 1000

class MyException(Exception):
    def __init__(self, message):
        Exception.__init__(self, message)
    def error(self):
        print self.message

try:
    z = x/y
    if(z<0.01):
        raise MyException("Number is too small")
except MyException, error:
    print "Caught MyException"
    print error.message
finally:
    print "I am always here"

Caught MyException
Number is too small
I am always here