David <[email protected]> wrote:
Hi, I am going through Wesley Chun's book and this is Exercise 8-11;
Write a program to ask the user to input a list of names, format "Last
Name" "comma" "First Name". Write a function that manages the input so
that when/if the user types in the names in the wrong format the error
is corrected, and keep track of the number of errors. When done sort the
list.
Questions;
This;
answers = raw_input('Enter Name: ')
index = answers.find(',')
Does not seem to be a very good to me, how could I check for a comma
between two words?
And This;
try:
total_names = int(raw_input('Enter Total Number of Names: '))
except ValueError:
print 'You must enter a number!'
total_names = int(raw_input('Enter Total Number of Names: '))
Does not handle the second input for exceptions.
thanks,
-david
#!/usr/bin/python
import string
names = []
def get_names():
wrong_format = 0
count = 0
try:
total_names = int(raw_input('Enter Total Number of Names: '))
except ValueError:
print 'You must enter a number!'
total_names = int(raw_input('Enter Total Number of Names: '))
while count < total_names:
print 'Format: LastName, First Name'
answers = raw_input('Enter Name: ')
index = answers.find(',')
answers = answers.title()
index = answers.find(',')
if index != -1:
names.append(answers)
count += 1
else:
wrong_format += 1
print '\nWrong Format!!!'
if wrong_format > 1:
print 'That is %i Fixing Format ...' % wrong_format
else:
print 'You have done this %i times, Fixing Format ...'
% wrong_format
print 'Done, continue:\n'
answers = answers.split()
answers = string.join(answers, ', ')
names.append(answers)
count += 1
def show_names():
print 'Your Names Are: \n'
for i in sorted(names):
print i
def main():
get_names()
if names:
show_names()
if __name__ == "__main__":
main()
For your second question, there are several things that could be wrong
with the user's input. Usually it's easiest to make that a separate
function to make it readable. Then the function returns whenever the
result passes its validation.
def getTotalNumber(prompt):
while True:
try:
numstr = raw_input(prompt)
n = int(numstr)
if 0 < n < 50: #some validation
return n
print "Number is not reasonable, try again"
except ValueError:
print "You must enter a number!"
This way there are two forms of validation happening. If the exception
fires, the user gets one print statement, and if the validation fails,
he gets the other.
The purist might complain that the return is in the middle of the
function, so if you want to fix that, move the return n to the end, and
change the existing one to a break..
The first question can be solved in a similar way, though the meaning of
"the error is corrected" is unclear. You can correct the error by
asking the user to fix it. Or you could take a wild guess that instead of
lastname, firstname
the user has entered
firstname lastname
But since many names have multiple spaces (Dr. William Smith, or
Henry James, Jr.) or even other punctuation, I'd think the only safe
thing would be to ask the user separately for the fields you want. And
each field may contain spaces or commas, or periods.
Anyway, since it's just an exercise, I'd probably model it the same way
as the first function, and just ask the user again. So the function
would look quite similar, with the one difference that it would return
an error count as well as the name. Then the main function would
accumulate the counts and print the summary at the end.
DaveA
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