write — Write numeric or text payloads to TCP client connections with MATLAB-compatible encoding behavior.

write(t, data, ...) sends binary or text payloads through a tcpclient connection while honoring MATLAB-compatible datatype conversion, byte-order handling, and timeout rules.

Syntax

count = write(client, data)
count = write(client, data, datatype)

Inputs

Returns

Errors

How write works

• write(t, data) converts data to unsigned 8-bit integers (the MATLAB default) and sends the bytes to the peer. The return value is the number of elements written when the caller requests an output argument.
• write(t, data, datatype) encodes the payload using the supplied MATLAB datatype token. Supported values mirror MATLAB: "uint8" (default), "int8", "uint16", "int16", "uint32", "int32", "uint64", "int64", "single", "double", "char", and "string". Numeric conversions saturate to the destination range just like MATLAB cast operations. "char" treats values as single-byte character codes and "string" encodes UTF-8 text.
• The client’s ByteOrder property controls how multi-byte numeric values are serialised. "little-endian" is the default, while "big-endian" matches the traditional network byte order.
• When the socket cannot send the entire payload before the timeout expires, write raises RunMat:write:Timeout. If the peer closes the connection before or during the transfer the builtin raises RunMat:write:ConnectionClosed and marks the client as disconnected.
• Inputs that originate on the GPU are gathered back to the host automatically before any bytes are written.

Does RunMat run write on the GPU?

Networking occurs on the host CPU. If data or the tcpclient struct resides on the GPU, RunMat gathers the values to host memory before converting them to bytes. Acceleration providers are not involved and the resulting payload remains on the CPU. Providers that support residency tracking automatically mark any gathered tensors as released.

Examples

Sending an array of bytes to an echo service

client = tcpclient("127.0.0.1", 50000);
count = write(client, uint8(1:4))

Expected output:

count =
     4

Writing doubles with explicit byte order

client = tcpclient("localhost", 50001, "ByteOrder", "big-endian");
values = [1.5 2.5 3.5];
write(client, values, "double")

Transmitting ASCII text

client = tcpclient("127.0.0.1", 50002);
write(client, "RunMat TCP", "char")

Sending UTF-8 encoded strings

client = tcpclient("127.0.0.1", 50003);
write(client, "Διακριτό", "string")

Handling connection closures

client = tcpclient("example.com", 12345, "Timeout", 0.25);
try
    write(client, uint8([1 2 3 4]));
catch err
    disp(err.identifier)
end

Expected output:

RunMat:write:ConnectionClosed

Using write with coding agents

Open a RunMat example with live inputs, then ask the agent to explain how write changes the result.

FAQ

Related Io functions

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how write is executed, line by line, in Rust.

• View the source for write in Rust on GitHub
• Learn how the RunMat runtime works
• Found a bug? Open an issue with a minimal reproduction.

About RunMat

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