Python入门:中file.seek函数的用法
2016-06-11 14:52
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file.seek是将文件游标移动到文件的任意位置,然后对文件的当前位置进行操作(增加、删除内容等)
offset:开始的偏移量,也就是代表需要移动偏移的字节数
whence:给offset参数一个定义,表示要从哪个位置开始偏移;0代表从文件开头开始算起,1代表从当前位置开始算起,2代表从文件末尾算起。
file.tell()方法的返回值就告诉大家当前文件游标的位置。
python3.*
>>> help(f.seek) Help on built-in function seek: seek(cookie, whence=0, /) method of _io.TextIOWrapper instance Change stream position. Change the stream position to the given byte offset. The offset is interpreted relative to the position indicated by whence. Values for whence are: * 0 -- start of stream (the default); offset should be zero or positive * 1 -- current stream position; offset may be negative * 2 -- end of stream; offset is usually negative Return the new absolute position.
python2.*
Help on built-in function seek: seek(...) seek(offset[, whence]) -> None. Move to new file position. Argument offset is a byte count. Optional argument whence defaults to 0 (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.
offset:开始的偏移量,也就是代表需要移动偏移的字节数
whence:给offset参数一个定义,表示要从哪个位置开始偏移;0代表从文件开头开始算起,1代表从当前位置开始算起,2代表从文件末尾算起。
file.tell()方法的返回值就告诉大家当前文件游标的位置。
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