为什么我的while循环停止了？

Question

I've been reading other posts and couldn't figure it out. No matter what I enter at the end of this repeat it always repeats the loop. I've tried while(repeat != "Quit" or repeat != "quit" or repeat != "b" or repeat != "B" or repeat != "no" or repeat != "No"): but it still never worked. I don't know what else to try. What's wrong with this while loop?

    repeat = "d"
    print "Please answer questions using the choices (A, B, C, etc.)"
    time.sleep(2.1738)
    while repeat != "Quit" or repeat != "quit" or repeat != "b" or repeat != "B" or repeat != "no" or repeat != "No":
        print "A) Round Edges"
        print "B) Straight Edges"
        Edges1 = raw_input("Does the shape have round edges or straight edges?: ")
        if Edges1 == "a" or Edges1 == "A" or Edges1 == "Round Edges" or Edges1 == "round edges":
            print "A) Circle"
            print "B) Semi-Circle"
            Circle = raw_input("Is it a circle or semi-circle?: ")
            if Circle == "A" or Circle == "a" or Circle == "Circle" or Circle == "circle":
                radius_C = input("What is the radius (1/2 of the Diameter)?: ")
                Area_C = math.pi * radius_C ** 2.0
                Circum_C = 2.0 * math.pi * radius_C
                Diameter_C = 2.0 * radius_C
                print "The radius is " + str(radius_C) + ". "
                time.sleep(.5)
                print "The diameter is " + str(Diameter_C) + ". "
                time.sleep(.5)
                print "The circumference is " + str(round(Circum_C, 2)) + ". "
                time.sleep(.5)
                print "The area is " + str(round(Area_C, 2)) + ". "
                time.sleep(5)
            elif Circle == "B" or Circle == "b" or Circle == "Semi-Circle" or Circle == "semi-circle":
                radius_S = input("What is the radius (1/2 of the Diameter)?: ")
                Area_S = math.pi * radius_S ** 2.0 * .5
                Diameter_S = 2 * radius_S
                Per_S = ((math.pi * 2 * radius_S) / 2) + Diameter_S
                print "The radius is " + str(radius_S) + ". "
                time.sleep(.5)
                print "The diameter is " + str(Diameter_S) + ". "
                time.sleep(.5)
                print "The perimeter is " + str(round(Per_S, 2)) + ". "
                time.sleep(.5)
                print "The area is " + str(round(Area_S, 2)) + ". "
                time.sleep(5)
            else:
                print "Incorrect input."
        elif Edges1 == "b" or Edges1 == "B" or Edges1 == "Straight Edges" or Edges1== "straight edges":
            sides = input("How many sides does the shape have?: ")
            sideL = input("What is the length of 1 side?: ")
            Area = round(Area_R(sides, sideL), 4)
            Perim = round(Perm_R(sides, sideL), 4)
            print "The area of this figure is: " + str(Area)
            print "The perimeter of the figure is: " + str(Perim)
        else:
            print "Incorrect input."


        time.sleep(4)
        print" "
        print" "
        print "A) yes"
        print "B) No"
        repeat = raw_input("Want to try another?: ")
        time.sleep(1)
main()

Answer 1

Well, let's take a look at that condition:

while repeat != "Quit" or repeat != "quit"

Think about it. No matter what the value of repeat is, this is always true . repeat will always be different from "Quit" OR FROM "quit" . If it's the one, it won't be the other.

You need it to be different from "Quit" AND FROM "quit". Try this:

while repeat != "Quit" and repeat != "quit" ...

Or, the more compact:

while repeat.lower() not in ["quit", "b"]

Answer 2

Replace your or's with and's like this:

while repeat != "Quit" and repeat != "quit" and repeat != "b" and repeat != "B" and repeat != "no" and repeat != "No":

It's always going to not equal at least one of those things. It can't equal two things at once. Here's another shorter example (but try my suggestion above).

# Never true
repeat == "Quit" and repeat == "quit"

# Never false
repeat != "Quit" or repeat != "quit"