如何修复函数内的while循环？

Question

我的代码有效，并要求命名文件，以及多少个数字。但它只是不断地询问数字，如果我输入零，它就会做它应该做的事情。非常感谢任何帮助。我只是不知道如何修复代码，这真的让我很烦恼。

import random
def generateRandomNumber(myfile):
    try:
        fileToBeWrittenTo = open(myfile,"w")
        numberOfRandomNumbers = int(input("How many numbers" + \
                                      " should the random file hold?:" ))
    except Exception as potentialError:
        print("An error has occured:", potentialError )
    else:
        for randomNumberCount in range(1, numberOfRandomNumbers + 1 ):
            randomNumber = generateRandomNumber(myfile)
            fileToBeWrittenTo.write(str( randomNumber ) + '\n' )
        print( numberOfRandomNumbers, "numbers have been written" + \
               " to the file ")
    finally:
        fileToBeWrittenTo.close()
        print("\nEnd of program")
    displayNumber(myfile)
    randomNumber = random.randint(1,500)
    return randomNumber

def main():
    myfile = str(input("Enter file name here "))
    with open(myfile, 'w+') as f:
        generateRandomNumber(myfile)

    return f
    myfile.close    

def displayNumber(myfile):
    try:
        myfile = open(myfile,'r')
        total = 0
        NORN = 0
        Avg = 0
        line = myfile.readline()
        while line != "":
            randomNumber = int(line)
            total += randomNumber
            NORN += 1
            Avg = total / NORN
            print( randomNumber )
        line = myfile.readline()
    except IOError:
        print("Problem with file being opened")
    else:
        print("The average of the numbers is " + str(Avg))
        print("The total of all the numbers is " + str(total)+\
          "\nThere are " + str(NORN)+\
          " in the file")
        myfile.close()
    finally:
        print("End of program")

main()

Answer 1

使用try-except-else-finally 很好，但我认为它会让你感到困惑，请先尝试学习try-except。

你没有结束循环

def generateRandomNumber(myfile):
    ....
            randomNumber = generateRandomNumber(myfile)

和

while line != "":
    ....
    print( randomNumber )
line = myfile.readline()

应该是

while line != "":
    ....
    print( randomNumber )
    line = myfile.readline()

这里是你的工作代码

import random

def generateRandomNumber():
    randomNumber = random.randint(1,500)
    return randomNumber

def writeRandom(myfile):
    try:
        fileToBeWrittenTo = open(myfile, "w")
        numberOfRandomNumbers = int(input("How many numbers" + \
                                      " should the random file hold?:" ))
    except Exception as potentialError:
        print("An error has occured:", potentialError )
    else:
        for randomNumberCount in range(1, numberOfRandomNumbers + 1 ):
            randomNumber = generateRandomNumber()
            fileToBeWrittenTo.write(str( randomNumber ) + '\n' )
        print( numberOfRandomNumbers, "numbers have been written" + \
               " to the file ")
        fileToBeWrittenTo.close()
        displayNumber(myfile)
    finally:
        print("\nEnd of program")

def main():
    myfile = str(input("Enter file name here "))
    writeRandom(myfile)  

def displayNumber(myfile):
    try:
        my_file = open(myfile,'r')
        total = 0
        NORN = 0
        Avg = 0
        line = my_file.readline()
        while line != "":
            randomNumber = int(line)
            total += randomNumber
            NORN += 1
            Avg = total / NORN
            print( randomNumber )
            line = my_file.readline()
    except IOError:
        print("Problem with file being opened")
    else:
        print("The average of the numbers is " + str(Avg))
        print("The total of all the numbers is " + str(total)+\
          "\nThere are " + str(NORN)+\
          " in the file")
        my_file.close()
    finally:
        print("End of program")

main()

Answer 2

generateRandomNumber 函数在 randomNumber = generateRandomNumber(myfile) 语句中递归调用自身，如果输入 0 则会跳过。

另外，您的main 包含一个未使用的with open，并且myfile.close 语句既不会执行也不需要。尝试缩短它。

def main():
    myfile = str(input("Enter file name here "))
    generateRandomNumber(myfile)

您还可以使用with open 显着简化generateRandomNumber 和displayNumber 函数。

处理文件时最好使用 with 关键字 对象。优点是文件在其后正确关闭 套件完成，即使在某些时候引发了异常。使用 with 也比编写等效的 try-finally 块要短得多

最后，displayNumber 包含一个无限循环，尝试将第二个line = myfile.readline() 缩进一步或重写函数以一次读取完整文件并使用简单的for 循环。

with open(myfile) as myfilehandle:
    lines = myfilehandle.readlines()

for line in lines:
    # do things