如何以用户输入结束循环，但不将其计入数字的总体平均值

Question

I am currently studying C++ but my friend sometimes sends me his past papers from his python studies so that I can try them out. I am currently having a small problem with one of the final questions. I must add and find the average of the numbers entered and end the loop when the user enters a certain number eg:-200.

I managed to find the average but it includes the -200 in the average and how many numbers where entered. I tried breaking the loop before it adds the -200 to the list and I tried adding 200 after its been added to the loop but it they both did not work.
This is what I have so far:

avg = []
count = 0
while True:
    x = float(input('Enter a number(interger or float) :'))
    avg.append(x)
    count +=1

    if x == -999:

        list = avg 
        sum(list)
        len(list)
        avg = float(sum(list))/len(list)
        print ('The average of', count, 'is ' "%0.2f" % avg)
        break

Answer 1

Try this

avg = []
count = 0
while True:
    x = float(input('Enter a number(interger or float) :'))
    if x == -999:
        list = avg 
        sum(list)
        len(list)
        avg = float(sum(list))/len(list)
        print ('The average of', count, 'is ' "%0.2f" % avg)
        break
    else:
        avg.append(x)
        count +=1

You just need to add the number to the list to be averaged after you have checked whether its the terminating number. You might not even need to put an else here since you are using break

Answer 2

Another option is reading the first value before entering the loop:

numbers = []
numbers.append(float(input('Enter a number(interger or float) :')))
#the last argument given is the one you check for exeting the loop
while avg[-1] != -999:
    numbers.append(float(input('Enter a number(interger or float) :')))
length = len(numbers)
avg = float(sum(numbers)/length)
print ('The average of', str(length) , 'is ' "%0.2f" % avg)

not sure if this is better but it is an option if you want to avoid checking the if statement every iteration