Python3錯誤-OSError: [Errno 22] Invalid argument

錯誤描述：

錯誤修復：

#報錯代碼行
 datafile = open('D:\PythonProject\DDU\TestFile\testdata\expect_digA_10.txt')

#修改方式1:
 datafile = open('D:\\PythonProject\\DDU\\TestFile\\testdata\\expect_digA_10.txt')

#修改方式2：
 datafile = open(r'D:\PythonProject\DDU\TestFile\testdata\expect_digA_10.txt')

#修改方式3：
 datafile = open('D:/PythonProject/DDU/TestFile/testdata/expect_digA_10.txt')