fseek
(PHP 4, PHP 5, PHP 7)
fseek — 在文件指针中定位
说明
fseek (
resource
$handle ,
int $offset [,
int $whence = SEEK_SET ] ) :
int
在与 handle 关联的文件中设定文件指针位置。 新位置从文件头开始以字节数度量，是以 whence 指定的位置加上 offset。
In general, it is allowed to seek past the end-of-file; if data is then written, reads in any unwritten region between the end-of-file and the sought position will yield bytes with value 0. However, certain streams may not support this behavior, especially when they have an underlying fixed size storage.
参数
返回值
成功则返回 0；否则返回 -1。注意移动到 EOF 之后的位置不算错误。
范例
Example #1 fseek() 例子
<?php
$fp = fopen('somefile.txt', 'r');
// read some data
$data = fgets($fp, 4096);
// move back to the beginning of the file
// same as rewind($fp);
fseek($fp, 0);
?>
注释
Note:
如果使用附加模试（a 或 a+），任何写入文件数据都会被附加上去，而文件的位置将会被忽略，调用 fseek() 的结果尚未定义。
Note:
Not all streams support seeking. For those that do not support seeking, forward seeking from the current position is accomplished by reading and discarding data; other forms of seeking will fail.
