WSANtohs function (winsock2.h)

Article
10/13/2021

The WSANtohs function converts a u_short from network byte order to host byte order.

Syntax

int WSAAPI WSANtohs(
  [in]  SOCKET  s,
  [in]  u_short netshort,
  [out] u_short *lphostshort
);

Parameters

[in] s

A descriptor identifying a socket.

[in] netshort

A 16-bit number in network byte order.

[out] lphostshort

A pointer to a 16-bit number to receive the number in host byte order.

Return value

If no error occurs, WSANtohs returns zero. Otherwise, a value of SOCKET_ERROR is returned, and a specific error code can be retrieved by calling WSAGetLastError.

Error code	Meaning
WSANOTINITIALISED	A successful WSAStartup call must occur before using this function.
WSAENETDOWN	The network subsystem has failed.
WSAENOTSOCK	The descriptor is not a socket.
WSAEFAULT	The lphostshort parameter is NULL or the address pointed to is not completely contained in a valid part of the user address space.

Remarks

The WSANtohs function takes a 16-bit number in network byte order and returns a 16-bit number in host byte order in the 16-bit number pointed to by the lphostshort parameter. The socket passed in the s parameter is used to determine the network byte order required based on the Winsock catalog protocol entry associated with the socket. This feature supports Winsock providers that use different network byte orders.

If the socket is for the AF_INET or AF_INET6 address family, the WSANtohs function can be used to convert an IP port number in network byte order to the IP port number in host byte order.

The WSANtohs function requires that the Winsock DLL has previously been loaded with a successful call to the WSAStartup function. For use with the AF_INET OR AF_INET6 address family, the ntohs function does not require that the Winsock DLL be loaded.

Windows Phone 8: This function is supported for Windows Phone Store apps on Windows Phone 8 and later.

Windows 8.1 and Windows Server 2012 R2: This function is supported for Windows Store apps on Windows 8.1, Windows Server 2012 R2, and later.

Requirements

Requirement	Value
Minimum supported client	Windows 8.1, Windows Vista [desktop apps \| UWP apps]
Minimum supported server	Windows Server 2003 [desktop apps \| UWP apps]
Target Platform	Windows
Header	winsock2.h
Library	Ws2_32.lib
DLL	Ws2_32.dll