Python，为什么我的循环将文本文件中的空白写入列表的末尾

Question

correctAnswers = ['A','C','A','A','D','B','C','A','C','B','A','D','C','A','D','C','B','B','D','A']

studentAnswers = []
correctList = []
file = open('forchapter7.txt','r')

student = file.readline()
student = student.rstrip('\n')
studentAnswers.append(student)

while student != '':

    student = file.readline()
    student = student.rstrip('\n')
    studentAnswers.append(student)

print(studentAnswers)
print(correctAnswers)


file.close()    

#displays this

['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', '']
['A', 'C', 'A', 'A', 'D', 'B', 'C', 'A', 'C', 'B', 'A', 'D', 'C', 'A', 'D', 'C', 'B', 'B', 'D', 'A']

my text file is a plain .txt file with the letters AT going down and no space or new line after T, why is my loop writing the blank space?

Answer 1

When you read your final line, student == 'T' , so the loop repeats itself. When you try to file.readline() after you have finished reading the entire file, it returns '' because there is nothing else to read. You are then adding this to your list.

Just add a check for empty string before adding to the list:

if student:
   studentAnswers.append(student)

EDIT: An alternative you could use is to read all the lines with file.readlines() and iterate over the list. This will not run the loop an extra time:

for student in file.readlines():
    studentAnswers.append(student.rstrip('\n')

You can even use list comprehension this way:

studentAnswers = [student.rstrip('\n') for student in file.readlines()]

Note, however, that if the file does have an empty line these last two methods will need checks to prevent them from adding an empty entry to the list.