(PHP 4, PHP 5, PHP 7)
ftell — 返回文件指针读/写的位置
$handle
) : int
返回由 handle 指定的文件指针的位置，也就是文件流中的偏移量。
Returns the position of the file pointer referenced by
handle as an integer; i.e., its offset into the file stream.
如果出错，返回 FALSE。
Example #1 ftell() 例子
<?php
// opens a file and read some data
$fp = fopen("/etc/passwd", "r");
$data = fgets($fp, 12);
// where are we ?
echo ftell($fp); // 11
fclose($fp);
?>