异常处理

s=raw_input("Input your age:")
if s=="":
    raise Exception("Input must no be empty.")
try:
    i=int(s)
except ValueError:
    print "Could not convert data to an integer."
except:
    print "Unknown exception!"
else: 
    print "You are %d "%i,"years old"
finally:#Clean up action
    print "Goodbye!"