La fonction open() est principalement utilisée pour le traitement de fichiers, généralement divisée en 3 Un processus suivant :
1. Ouvrir le fichier
2. Manipuler le fichier
3. Fermer le fichier
. Exemples de formats courants :
f = open('note.txt','r') f.read() f.close()
文件句柄 = open('文件路径','模式')
Les modes courants sont :
1.'r', lecture seule
2.'w', écriture uniquement (lorsque l'opération d'écriture seule est effectuée à l'ouverture, le contenu original du fichier sera effacé, veuillez faire attention à la sauvegarde)
3. 'a', ajouter
" " signifie qu'un fichier peut être lu et écrit en même temps
1.'r '
2 .'w '
3.'a '
"b" signifie traiter des fichiers binaires
1.'rb', 'rb'
2.'wb','wb '
3.'ab','ab '
"U" signifie que r n rn peut être automatiquement converti en n lors de la lecture (utilisé avec le mode r ou r)
1.'rU'
2.'r U'
class file(object)
def close(self): # real signature unknown; restored from __doc__
关闭文件
"""
close() -> None or (perhaps) an integer. Close the file.
Sets data attribute .closed to True. A closed file cannot be used for
further I/O operations. close() may be called more than once without
error. Some kinds of file objects (for example, opened by popen())
may return an exit status upon closing.
"""
def fileno(self): # real signature unknown; restored from __doc__
文件描述符
"""
fileno() -> integer "file descriptor".
This is needed for lower-level file interfaces, such os.read().
"""
return 0
def flush(self): # real signature unknown; restored from __doc__
刷新文件内部缓冲区
""" flush() -> None. Flush the internal I/O buffer. """
pass
def isatty(self): # real signature unknown; restored from __doc__
判断文件是否是同意tty设备
""" isatty() -> true or false. True if the file is connected to a tty device. """
return False
def next(self): # real signature unknown; restored from __doc__
获取下一行数据，不存在，则报错
""" x.next() -> the next value, or raise StopIteration """
pass
def read(self, size=None): # real signature unknown; restored from __doc__
读取指定字节数据
"""
read([size]) -> read at most size bytes, returned as a string.
If the size argument is negative or omitted, read until EOF is reached.
Notice that when in non-blocking mode, less data than what was requested
may be returned, even if no size parameter was given.
"""
pass
def readinto(self): # real signature unknown; restored from __doc__
读取到缓冲区，不要用，将被遗弃
""" readinto() -> Undocumented. Don't use this; it may go away. """
pass
def readline(self, size=None): # real signature unknown; restored from __doc__
仅读取一行数据
"""
readline([size]) -> next line from the file, as a string.
Retain newline. A non-negative size argument limits the maximum
number of bytes to return (an incomplete line may be returned then).
Return an empty string at EOF.
"""
pass
def readlines(self, size=None): # real signature unknown; restored from __doc__
读取所有数据，并根据换行保存值列表
"""
readlines([size]) -> list of strings, each a line from the file.
Call readline() repeatedly and return a list of the lines so read.
The optional size argument, if given, is an approximate bound on the
total number of bytes in the lines returned.
"""
return []
def seek(self, offset, whence=None): # real signature unknown; restored from __doc__
指定文件中指针位置
"""
seek(offset[, whence]) -> None. Move to new file position.
Argument offset is a byte count. Optional argument whence defaults to
(offset from start of file, offset should be >= 0); other values are 1
(move relative to current position, positive or negative), and 2 (move
relative to end of file, usually negative, although many platforms allow
seeking beyond the end of a file). If the file is opened in text mode,
only offsets returned by tell() are legal. Use of other offsets causes
undefined behavior.
Note that not all file objects are seekable.
"""
pass
def tell(self): # real signature unknown; restored from __doc__
获取当前指针位置
""" tell() -> current file position, an integer (may be a long integer). """
pass
def truncate(self, size=None): # real signature unknown; restored from __doc__
截断数据，仅保留指定之前数据
"""
truncate([size]) -> None. Truncate the file to at most size bytes.
Size defaults to the current file position, as returned by tell().
"""
pass
def write(self, p_str): # real signature unknown; restored from __doc__
写内容
"""
write(str) -> None. Write string str to file.
Note that due to buffering, flush() or close() may be needed before
the file on disk reflects the data written.
"""
pass
def writelines(self, sequence_of_strings): # real signature unknown; restored from __doc__
将一个字符串列表写入文件
"""
writelines(sequence_of_strings) -> None. Write the strings to the file.
Note that newlines are not added. The sequence can be any iterable object
producing strings. This is equivalent to calling write() for each string.
"""
pass
def xreadlines(self): # real signature unknown; restored from __doc__
可用于逐行读取文件，非全部
"""
xreadlines() -> returns self.
For backward compatibility. File objects now include the performance
optimizations previously implemented in the xreadlines module.
"""
pass
Python 2.xFichier d'opération python2
class TextIOWrapper(_TextIOBase):
"""
def close(self, *args, **kwargs): # real signature unknown
关闭文件
pass
def fileno(self, *args, **kwargs): # real signature unknown
文件描述符
pass
def flush(self, *args, **kwargs): # real signature unknown
刷新文件内部缓冲区
pass
def isatty(self, *args, **kwargs): # real signature unknown
判断文件是否是同意tty设备
pass
def read(self, *args, **kwargs): # real signature unknown
读取指定字节数据
pass
def readable(self, *args, **kwargs): # real signature unknown
是否可读
pass
def readline(self, *args, **kwargs): # real signature unknown
仅读取一行数据
pass
def seek(self, *args, **kwargs): # real signature unknown
指定文件中指针位置
pass
def seekable(self, *args, **kwargs): # real signature unknown
指针是否可操作
pass
def tell(self, *args, **kwargs): # real signature unknown
获取指针位置
pass
def truncate(self, *args, **kwargs): # real signature unknown
截断数据，仅保留指定之前数据
pass
def writable(self, *args, **kwargs): # real signature unknown
是否可写
pass
def write(self, *args, **kwargs): # real signature unknown
写内容
pass
Python 3.xFichier d'opération python3
Mais dans en fait, il n'y a que quelques opérations couramment utilisées :
f.read(3) # python2中表示指定读取3个字节，python3中表示指定读取3个字符！ f.readline() # 读取文件内容中的一行 f.readlines() # 自动将文件内容解析为一个< 行的列表 >，可以用 for line in f.readlines(): 处理 f.write('helloPython') f.seek(9) # 按照字节来执行，用来指定当前文件指针位置,seek(0)表示文件指针移到文件头，seek(0,2)指向文件尾，便于追加内容 f.tell() # 是按照字节来执行的，用来查看当前指针位置
Il existe également une fonction truncate(), qui permet de tronquer le contenu du fichier et de ne conserver le contenu qu'avant la troncature du contenu du fichier. Ce n'est pas facile à comprendre. Vous pouvez voir l'exemple :
f = open('test.log','r+',encoding='utf-8') # encoding='utf-8'，有处理汉字的时候这样用 f.seek(9) # 原文件内容是‘小苹果helloPython’ f.truncate() #执行truncate()后，仅保留原文件截断之前的内容，这里即为‘小苹果’ f.close()
Lors de l'utilisation de la fonction open() pour le traitement de fichiers ci-dessus, vous devez exécuter f.close() pour fermer le fichier après l'avoir ouvert pour l'opération, ce qui est très gênant. L'utilisation de l'instruction with() peut éviter cette opération fastidieuse et fermer automatiquement le fichier après l'opération sur le fichier. De plus, le but de l'introduction de l'instruction with en python est de supprimer tous les mots-clés try, except et finalement dans la Gestion des exceptions, ainsi que le code lié à l'allocation et à la libération des ressources, réduisant ainsi la quantité de code. écrit et rend le code plus concis !
Par exemple :
with open('name.txt', 'w') as f:
f.write('Somebody^Fancy1')est équivalent à :
try:
f = open('name.txt','w')
f.write('Somebody^Fancy1')
finally:
if f:
f.close()Ce qui précède est le contenu détaillé de. pour plus d'informations, suivez d'autres articles connexes sur le site Web de PHP en chinois!
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