我怎样才能从平均成绩中排除我的计数呢？

Question

我想知道当我想显示我的文件时如何计数，但不想把计数加到我的平均成绩中

def main():
    choice = "q"
    while choice != "X":
        print_menu()
        choice = input("Enter an option (D, C, X): ")
        if choice == "D":
            DisplayScores()
        elif choice == "C":
            CalcAverage()

def print_menu():
    print("D. Display Grades")
    print("C. Calculate Average")
    print("X. Exit Application")

def DisplayScores():
    try:
        infile = open("data.txt",'r')
        count = 0
        for line in infile:
            count += 1
            print(count,line.rstrip("\n"))
            line = infile.readline() 
        infile.close()
    except IOError:
        print("File does not exist.")
    except:
        print("Unknown error.")

def CalcAverage():
    Average = 0.0
    try:
        datafile = open("data.txt", 'r')
        for grade in datafile:
            total = float(grade)
            Average += total
            print("The average of the class is: ", format(Average/29, '.2f'))
    except IOError:
        print("Something is wrong with the file.")
        print("Unknown Error.")
    datafile.close()

main()

Answer 1

为什么每次循环都要打印平均值？在循环完成之前，你不可能知道平均值是多少。此外，最好是除以文件中的实际分数，而不是假设为29。请尝试以下方法：

total = 0.0
grades = 0
try:
    datafile = open("data.txt", 'r')
    for grade in datafile:
        grades += 1
        total += float(grade)
    print("The average of the class is: ", format(total/grades, '.2f'))