Question

I want to apply this while loop into the for loop below.
I have tried putting the while loop before the if statements, in each if statement.
When i put it before the if statement( in the for loop ) it asks the user once and then returns the same input for the whole range (1,8).
I want this while loop to apply to each question, the seven items 2 to 8
how do i implement it. can anyone help please, Thanks

def valid_entry ():
    price = 110
    invalid_input = 1
    while price< 0 or price> 100:
        if invalid_input >=2:
            print "This is an invalid entry"
            print "Please enter a number between 0 and 100"
        try:
            price= int(raw_input("Please enter your price  : "))
        except ValueError:
            price = -1   
        invalid_input +=1 

End of the while loop

def prices ():   
    x = range (1,8)
    item=2
    price=0
    for item in x:
        item +=1
        print "\n\t\titem",item
        price = int(raw_input("Enter your price : "))
        if price <10:
            price=1
            print "This is ok"


        if price >9 and price <45:
            price +=5
            print "This is great"


        if price >44 and price <70:
            price +=15
            print "This is really great"

        if price >69:
            price +=40
            print "This is more than i expected"

    print "\nYou now have spent a total of ",price

prices ()    

Is the lack of responses a sign that its a stupid question or is it not possible to do?

does this make it any clearer ?

def prices ():   
    x = range (1,8)
    item=2
    price=0
    for item in x:
        item +=1
        print "\n\t\titem",item
        valid_entry ()#should it go here
        price = int(raw_input("Enter your price : "))
        valid_entry ()#should it go here
        if price <10:
           valid_entry ()#should it go here and so on for the following 3 if conditions
            price=1
            print "This is ok"


        if price >9 and price <45:
            price +=5
            print "This is great"


        if price >44 and price <70:
            price +=15
            print "This is really great"

        if price >69:
            price +=40
            print "This is more than i expected"

    print "\nYou now have spent a total of ",price

Answer 1

You could try something like this (apologies if this isn’t what you were looking for). Happy to explain anything that doesn’t make sense – overall idea is that it loops through a range of 8 items, asking for a valid price each time and continuing to ask if the entered value is either not a number or not in the specified range. As this may be for an assignment, I tried to keep it as closely aligned to the concepts you already demonstrated that you knew (the only exception here may be continue):

def valid_entry():
    # Here we define a number of attempts (which is what I think
    # you were doing with invalid_input). If the person enters 10
    # invalid attempts, the return value is None. We then check to
    # see if the value we get back from our function is None, and if
    # not, proceed as expected.
    num_attempts = 0
    while num_attempts < 10:
        # Here we do the input piece. Note that if we hit a ValueError,
        # the 'continue' statement skips the rest of the code and goes
        # back to the beginning of the while loop, which will prompt
        # again for the price.
        try:
            price = int(raw_input("Enter your price : "))
        except ValueError:
            print 'Please enter a number.'
            num_attempts += 1
            continue

        # Now check the price, and if it isn't in our range, increment
        # our attempts and go back to the beginning of the loop.
        if price < 0 or price > 100:
            print "This is an invalid entry"
            print "Please enter a number between 0 and 100"
            num_attempts += 1
        else:
            # If we get here, we know that the price is both a number
            # and within our target range. Therefore we can safely return
            # this number.
            return price

    # If we get here, we have exhausted our number of attempts and we will
    # therefore return 'None' (and alert the user this is happening).
    print 'Too many invalid attempts. Moving to the next item.'
    return None


def prices():
    # Here we go from 1-8 (since the upper bound is not included when
    # using range).
    x = range(1,9)

    # Here we use a variable (total) to store our running total, which will
    # then be presented at the end.
    total = 0

    # Now we iterate through our range.
    for item in x:
        print "\n\t\titem",item

        # Here is the important part - we call our valid_entry function and
        # store the result in the 'price' variable. If the price is not
        # None (which as we saw is the return value if the number of attempts
        # is > 10), we proceed as usual.
        price = valid_entry()
        if price is not None:
            if price <10:
                # Note this should probably be += 1
                total += 1
                print "This is ok"

            elif price >= 10 and price < 45:
                total += 5
                print "This is great"

            elif price >= 45 and price < 70:
                total += 15
                print "This is really great"

            # We know that price >= 70 here
            else:
                total += 40
                print "This is more than i expected"

    # Now print out the total amount spent
    print "\nYou now have spent a total of ", total

prices()