Python：循环校验文件存在、main传文件名给readdata及计算平均分

我尝试校验当前目录下的文件是否存在，若存在则读取该文件，但代码存在问题。希望实现：

• 在while循环中校验文件是否存在并读取
• 从main函数向readdata传递文件名
• 计算文件中3名学生的平均分

原代码 #

import os.path
def readdata():
    isFileExist = False
    while isFileExist == False:
        userIN = str(input("Please Enter a file name, followed by .txt: "))
    isExist = os.path.exists(userIN)
        if isFileExistExist == False:
            print(f"Checking... {userIN} DOES NOT exist in the current directory. Please retry.")
        else:
            print(f"Checking... {userIN} exist in the current directory.")
print(f"\n      The file < {userIN} > includes the following data:")
IN = open(userIN,"r")
std1N = IN.readline()
std1M = IN.readline()
std2N = IN.readline()
std2M = IN.readline()
std3N = IN.readline()
std3M = IN.readline()
IN.close()
print(f"      Student Name: {std1N.strip()}")
print(f"      Performance: {std1M.strip()} out of 100")
print(f"      Student Name: {std2N.strip()}")
print(f"      Performance: {std2M.strip()} out of 100")
print(f"      Student Name: {std3N.strip()}")
print(f"      Performance: {std3M.strip()} out of 100")
print(f"      The average exam score of the 3.0 students in the file < {userIN} > is {(eval(s1M.strip())+eval(s2M.strip())+eval(s3M.strip()))/3:.2f}.")

def main():
    readdata()

if __name__ == '__main__':
    main()

修改后的完整代码 #

import os.path

def readdata(filename):
    # 读取文件内容并收集学生数据
    students = []
    with open(filename, "r") as file:
        # 按姓名+分数的配对读取数据
        while True:
            name_line = file.readline()
            score_line = file.readline()
            # 读到文件末尾或无有效数据时停止
            if not name_line or not score_line:
                break
            name = name_line.strip()
            score = score_line.strip()
            if name and score.isdigit():
                students.append({"name": name, "score": int(score)})
    
    # 输出学生信息
    print(f"\n      The file < {filename} > includes the following data:")
    for student in students:
        print(f"      Student Name: {student['name']}")
        print(f"      Performance: {student['score']} out of 100")
    
    # 计算并输出平均分
    if students:
        total_score = sum(student["score"] for student in students)
        average_score = total_score / len(students)
        print(f"      The average exam score of the {len(students)} students in the file < {filename} > is {average_score:.2f}.")

def main():
    filename = ""
    is_file_exist = False
    # 在循环中校验文件存在性，直到输入有效文件
    while not is_file_exist:
        filename = input("Please Enter a file name, followed by .txt: ")
        is_file_exist = os.path.exists(filename)
        if not is_file_exist:
            print(f"Checking... {filename} DOES NOT exist in the current directory. Please retry.")
        else:
            print(f"Checking... {filename} exists in the current directory.")
    # 将文件名传递给readdata函数
    readdata(filename)

if __name__ == '__main__':
    main()

关键实现说明 #

• 循环校验文件存在：把文件存在性判断逻辑放在main函数的while循环中，直到用户输入的文件存在才退出循环，确保后续处理的文件有效。
• main向readdata传递文件名：修改readdata函数，添加filename参数，main函数在确认文件存在后，将文件名作为参数传入，避免使用全局变量，代码更规范。
• 计算平均分：
  1. 使用with语句自动管理文件资源，无需手动关闭文件，避免资源泄漏。
  2. 用列表动态收集学生数据，即使文件中不是刚好3个学生也能兼容处理。
  3. 通过sum()函数计算总分，除以学生数量得到平均分，替换原代码中错误的变量名和不安全的eval函数，直接将分数转为整数更安全可靠。
• 修复原代码问题：修正了缩进错误、变量名拼写错误（如isFileExistExist、s1M），优化了数据读取的容错逻辑。

内容的提问来源于stack exchange，提问作者noobatprogramming