PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8
socket_write - Write to a socket

socket_write( Socket$socket, string$data, [int|null$length = null] ): int|false

The function socket_write writes to the socket from the given data.




The buffer to be written.


The optional parameter length can specify an alternate length of bytes written to the socket. If this length is greater than the buffer length, it is silently truncated to the length of the buffer.

Return Values

Returns the number of bytes successfully written to the socket or false on failure. The error code can be retrieved with socket_last_error. This code may be passed to socket_strerror to get a textual explanation of the error.


It is perfectly valid for socket_write to return zero which means no bytes have been written. Be sure to use the === operator to check for false in case of an error.



socket_write does not necessarily write all bytes from the given buffer. It's valid that, depending on the network buffers etc., only a certain amount of data, even one byte, is written though your buffer is greater. You have to watch out so you don't unintentionally forget to transmit the rest of your data.


Version Description
8.0.0 socket is a Socket instance now; previously, it was a resource.
8.0.0 length is nullable now.

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