Python-如何在循环中多次使用扫描仪？

Question

I am trying to learn Python and I was trying to test what I just learned with a simple program. The program asks the user how many numbers they want to enter and then the program will use a loop to store the amount of numbers and find the average.

numberOfTimes = int(input("How many numbers do you want to use today? "))

count = 0

while(count < numberOfTimes):
    numberInput = int(input("Enter the number: "))
    count += 1

print((numberInput + numberInput + numberInput) / (count))

How do I get numberInput to store each variable? Thanks for the help in advanced!

Answer 1

您可以在循环的上方声明一个类似于totalNumber的变量，然后在循环中要做的就是以下操作：

totalNumber += int(input("Enter your number: ")

Answer 2

You don't need to store all the numbers, just sum them as you go:

count = 0
total = 0

while(count < numberOfTimes):
    total += int(input("Enter the number: "))
    count += 1

print(total / count)

Answer 3

Congrats for learning python, it's a great language.

So if you want to have the biggest flexibility you should save your numbers in a list.

A list in python behaves like a classically known array list (eg in java) because it can be accessed by index and it can be extended and has no fixed length.

So using a list you can add every number into a list:

numbers = list()

while(count < numberOfTimes):
    numberInput = int(input("Enter the number: "))
    numbers.append(numberInput)
    count += 1

Since you are now using a list of variable length you could also use the lengths ( len(mylist) list to determine the end of the while loop:

numbers = list()

while(len(numbers) < numberOfTimes):
    numberInput = int(input("Enter the number: "))
    numbers.append(numberInput)

Combining all these steps:

numberOfTimes = int(input("How many numbers do you want to use today? "))
numbers = list()

while(len(numbers) < numberOfTimes):
    numberInput = int(input("Enter the number: "))
    numbers.append(numberInput)

print( sum(numbers) / len(numbers) )

I added a little functionality to make it easier eg sum(numbers) is a build in function than sums up all the integers in the list and len(numbers) again replacing the counter.

Executing the program like that will show you quite quick, that you only get integer numbers as result which are not the correct average, here a you need to know that dividing two integers in python results in an integer which is most of the time not the result you want. There is a trick, cast one of the numbers (or both) to be floats, then divide:

average = float(sum(numbers)) / len(numbers)
print(average)

If you want to try some more steps you could eg get rid of the first question to ask for an amount of numbers by jumping out of the while loop depending on the content you type in:

print("Write some numbers, I will calculate the average. Finish with 'enter'")
numbers = list()

while(True):
    myinput = raw_input("Enter a number: ")
    if myinput == '':
        break
    numberInput = int(myinput)
    numbers.append(numberInput)

average = float(sum(numbers)) / len(numbers)
print(average)

The changes are this time: use raw_input instead of input which would be recommended, the while loop runs for ever if it doesn't get to the break which is executed if you don't give any input but just hit enter and the initial question for the count obviously is missing.