(PHP 4 >= 4.3.2, PHP 5, PHP 7)
streamWrapper::stream_read — Read from stream
$count
)This method is called in response to fread() and fgets().
Note:
Remember to update the read/write position of the stream (by the number of bytes that were successfully read).
countHow many bytes of data from the current position should be returned.
If there are less than count
bytes available, return as many as are available. If no
more data is available, return either FALSE or an
empty string.
调用此方法失败将给出
E_WARNING（未实现）。
Note:
If the return value is longer then
countanE_WARNINGerror will be emitted, and excess data will be lost.
Note:
streamWrapper::stream_eof() is called directly after calling streamWrapper::stream_read() to check if EOF has been reached. If not implemented, EOF is assumed.
When reading the whole file (for example, with file_get_contents()), PHP will call streamWrapper::stream_read() followed by streamWrapper::stream_eof() in a loop but as long as streamWrapper::stream_read() returns a non-empty string, the return value of streamWrapper::stream_eof() is ignored.