无限循环和添加raw_input结果的问题

Question

Right now, I am trying some exercises in looping process. Unfortunately, I bumped into some problems and wish all of you can help me.

The question:

Write a script which has these output:

Welcome to the receipt program!
Enter the value for the seat ['q' to quit]: five
I'm sorry, but 'five' isn't valid. Please try again.
Enter the value for the seat ['q' to quit]: 12
Enter the value for the seat ['q' to quit]: 15
Enter the value for the seat ['q' to quit]: 20
Enter the value for the seat ['q' to quit]: 30
Enter the value for the seat ['q' to quit]: 20
Enter the value for the seat ['q' to quit]: q

Total: $97

Here is my code:

print "Welcome to the receipt program"
while True:
    value = raw_input('Enter the value for the seat [Press q to quit]: ')

    if value == 'q':
        break

    print 'total is {}'.format(value)
    while not value.isdigit():
        print "I'm sorry, but {} isn't valid.".format(value)
        value = raw_input("Enter the value for the seat ['q' to quit]: ")

The problem I am facing:

1. When I run the code, I pressed q. Nothing shows up.
2. How can I add the total amount of the value if value == 'q'?

Answer 1

You are printing your total within the loop, while you want to do it in the end. Also, you want to accumulate your total:

print "Welcome to the receipt program"

total = 0
while True:
    value = raw_input('Enter the value for the seat [Press q to quit]: ')

    if value == 'q':
        break

    if value.isdigit():
        total += int(value)
    else:
        print "I'm sorry, but {} isn't valid.".format(value)

print 'total is {}'.format(total)