The write() call writes data from a buffer on a socket with descriptor s. The write() call applies only to connected sockets.

This call writes up to len bytes of data.

If there is not enough available buffer space to hold the socket data to be transmitted and the socket is in blocking mode, write() blocks the caller until more buffer space is available. If the socket is in nonblocking mode, write() returns a -1 and sets errno to EWOULDBLOCK. See fcntl() or ioctl() to set nonblocking mode.

For datagram sockets, this call sends the entire datagram, providing the datagram can fit into the TCP/IP buffers. Stream sockets act like streams of information with no boundaries separating data. For example, if an application wants to send 1000 bytes, each call to this function can send 1 byte, or 10 bytes, or the entire 1000 bytes. Therefore, applications using stream sockets should place this call in a loop, and call this function until all data has been sent.

#include <manifest.h>
#include <socket.h>
 
int write(int s, char *buf, int len)

Parameter

Description

s

Socket descriptor.

buf

Points to the buffer holding the data to be written.

len

Length in bytes of buf.

Return values

Related calls

connect(), fcntl(), getsockopt(), ioctl(), read(), readv() recv(), recvfrom(), recvmsg(), select(), selectex(), send(), sendmsg(), sendto(), setsockopt(), socket(), writev()