Question

我遇到一些错误，无法弄清楚如何用下面的程序修复，这里是它的说明。 “写一个程序，提示输入两个文件名并交换两个文件的内容。您的程序应足够健壮，如果文件不存在，该程序将重新提示。”

以下是我尝试运行它时遇到的错误。如果找不到文件，显然我也仍然需要重新提示用户。我尝试了一些方法使其正常工作，但也无法使其正常工作。

Traceback (most recent call last):
  File "C:\Users\istal\Desktop\6.2.py", line 30, in <module>
    dataobject.transfer(firstfilename,secondfilename)
  File "C:\Users\istal\Desktop\6.2.py", line 5, in transfer
    with open(firstfilename,'r')as filedata:
FileNotFoundError: [Errno 2] No such file or directory: 'C:/Users/istal/Desktop/python/testone.tx'

这是代码本身

class DataTransferinFiles():
def transfer(self,firstfilename,secondfilename):
    print("your first file is=",firstfilename);
    print("your second file is =", secondfilename)
    with open(firstfilename,'r')as filedata:
        firstfiledata= filedata.readlines()
        print()
        print("1st file reading complete")
        print()
    with open(secondfilename, 'r')as filedata:
        secondfiledata=filedata.readlines()
        print("2st file reading complete")

    for eachline in firstfiledata:
       filesecond = open(secondfilename,'a')
       filesecond.write("/n"+eachline+ "/n")
       print ("1st file transfered in to second file")

    for eachline in secondfiledata:
        filefirst = open(firstfilename)
        filefirst.write("\n"+eachline+ "\n")
        print ("second file transfered in to first file")

dataobject = DataTransferinFiles()

firstfilename = input("enter first file name for transfer")
secondfilename = input("enter second file name for transfer")


dataobject.transfer(firstfilename,secondfilename)

Answer 1

这是缩进的错字。

该行：

        dataobject = DataTransferinFiles()

应该只是：

    dataobject = DataTransferinFiles()

完整的代码：

class DataTransferinFiles():
    def transfer(self,firstfilename,secondfilename):
        print("your first file is=",firstfilename);
        print("your second file is =", secondfilename)
        with open(firstfilename,'r')as filedata:
            firstfiledata= filedata.readlines()
            print()
            print("1st file reading complete")
            print()
        with open(secondfilename, 'r')as filedata:
            secondfiledata=filedata.readlines()
            print("2st file reading complete")

        for eachline in firstfiledata:
           filesecond = open(secondfilename,'a')
           filesecond.write("/n"+eachline+ "/n")
           print ("1st file transfered in to second file")

        for eachline in secondfiledata:
            filefirst = open(firstfilename)
            filefirst.write("\n"+eachline+ "\n")
            print ("second file transfered in to first file")

dataobject = DataTransferinFiles()

firstfilename = input("enter first file name for transfer")
secondfilename = input("enter second file name for transfer")


dataobject.transfer(firstfilename,secondfilename)

Answer 2

我看到几个问题。

在for eachline in...块中，您尝试重新打开尚未关闭的文件。打开with进行写操作时，添加一个with上下文管理器，方法与第一次使用for eachline in secondfiledata上下文管理器相同。否则，您每次写一行时都会尝试打开文件。
readlines()不会像第一个那样追加-因此，如果您成功关闭文件，则只需覆盖直到最后一行。
您通过使用read()的{{1}} instad使此过程变得过于复杂。
这假定您正在文件中读写文本。如果是二进制文件怎么办？

我建议仔细阅读https://docs.python.org/3.3/tutorial/inputoutput.html#reading-and-writing-files

编写一个程序，提示输入两个文件名并交换两个文件的内容

2 个答案: