# poll.h - [Overview](#section491284639165628) - [Summary](#section924043502165628) - [Data Structures](#nested-classes) - [Macros](#define-members) - [Typedefs](#typedef-members) - [Functions](#func-members) ## **Overview** **Related Modules:** [IO](IO.md) **Description:** Declares I/O multiplexing functions. You can use the functions provided in this file to perform I/O multiplexing. **Since:** 1.0 **Version:** 1.0 ## **Summary** ## Data Structures

Data Structure Name

Description

pollfd

Defines I/O multiplexing.

## Macros

Macro Name and Value

Description

POLLIN 0x001

POLLIN event.

POLLPRI 0x002

POLLPRI event.

POLLOUT 0x004

POLLOUT event.

POLLERR 0x008

POLLERR event.

POLLHUP 0x010

POLLHUP event.

POLLNVAL 0x020

POLLNVAL event.

## Typedefs

Typedef Name

Description

nfds_t

typedef unsigned long

Number of poll types.

## Functions

Function

Description

poll (struct pollfd fds[], nfds_t nfds, int timeout)

int

Defines the I/O multiplexing system.