socket_write()

(PHP 4 >= 4.1.0, PHP 5, PHP 7)

Write to a socket

说明

The function socket_write() writes to the$socketfrom the given$buffer.

参数

The buffer to be written.

The optional parameter$lengthcan 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.

返回值

Returns the number of bytes successfully written to the socket 或者在失败时返回FALSE. 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.

注释

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.

参见

• socket_accept()Accepts a connection on a socket
• socket_bind()给套接字绑定名字
• socket_connect()开启一个套接字连接
• socket_listen()Listens for a connection on a socket
• socket_read()Reads a maximum of length bytes from a socket
• socket_strerror()Return a string describing a socket error

Here we have the same function to write a socket but with improved performance.
If the messager are not larger, they will be written entirely with a single socket_write() call. And is not needed to call the substr() function for the first bucle. 

I often read in php docs users not checking for the php function returned value, and in the case of socket_write, I could not see here in the comment anyone botering to read on the socket the server reply.
Then one user thought it would be a good idea to use usleep after a socket_write on a smtp connection.
Actually, if you check the server reply, not only will it give time for the server to reply before you write again on the socket, but also this is a great opportunity to check what the server replied you.
For instance, for smtp connection :
In this example MAIL_SERVER, MAIL_PORT and DEBUG are constants I defined.

witch worked at least, and 

wich made the server stop sending any data.
I hope this helps to save a lot of time. I needed about two days to find out, that this was the problem ;)

Some clients (Flash's XMLSocket for example) won't fire a read event until a new line is recieved.

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