fileno()method是Python中的一种内置方法,用于获取文件编号,即文件描述符作为流的整数。如果操作系统不使用文件的文件描述符,则可能会返回错误。
语法:
file_object.fileno()
Parameter(s):
它不接受任何参数。
返回值:
此方法的返回类型为<class'int'>,它返回一个整数值,该整数值是文件的文件描述符。
范例1:
# 带有示例的Python File fileno()方法 # 创建两个文件 myfile1 = open("hello1.txt", "w") myfile2 = open("hello2.txt", "w") # 打印文件描述符 print("files are in write mode...") print("myfile1.fileno(): ", myfile1.fileno()) print("myfile2.fileno(): ", myfile2.fileno()) # 关闭文件 myfile1.close() myfile2.close() # 在读取模式下打开文件 myfile1 = open("hello1.txt", "r") myfile2 = open("hello2.txt", "r") # 打印文件描述符 print("files are in read mode...") print("myfile1.fileno(): ", myfile1.fileno()) print("myfile2.fileno(): ", myfile2.fileno()) # 关闭文件 myfile1.close() myfile2.close()
输出结果
files are in write mode... myfile1.fileno(): 5 myfile2.fileno(): 6 files are in read mode... myfile1.fileno(): 5 myfile2.fileno(): 6
范例2:
# 带有示例的Python File fileno()方法 # 创建一个文件 myfile1 = open("hello1.txt", "w") # 打印文件描述符 print("myfile1.fileno(): ", myfile1.fileno()) # 关闭文件 myfile1.close() # 尝试打印文件描述符 # 关闭文件后 # 错误将被返回 # 打印文件描述符 print("myfile1.fileno(): ", myfile1.fileno())
输出结果
myfile1.fileno(): 5 Traceback (most recent call last): File "main.py", line 16, in <module> print("myfile1.fileno(): ", myfile1.fileno()) ValueError: I/O operation on closed file