getprotobynumber() — Get a protocol entry by number
Standards
| Standards / Extensions | C or C++ | Dependencies |
|---|---|---|
XPG4.2 |
both |
Format
#define _XOPEN_SOURCE_EXTENDED 1
#include <netdb.h>
struct protoent *getprotobynumber(int proto);#define _OE_SOCKETS
#include <netdb.h>
struct protoent *getprotobynumber(int proto);General description
- Parameter
- Description
- proto
- The protocol number.
The getprotobynumber() call returns a pointer to a protoent structure for the network protocol specified on the call. getprotobyname(), getprotobynumber(), and getprotoent() all use the same static area to return the protoent structure. This static area is only valid until the next one of these functions is called on the same thread.
- Element
- Description
- p_aliases
- An array, terminated with a NULL pointer, of alternative names for the protocol.
- p_name
- The official name of the protocol.
- p_proto
- The protocol number.
Special behavior for C++: To use this function with C++, you must use the _XOPEN_SOURCE_EXTENDED 1 feature test macro.
Returned value
If successful, getprotobynumber() returns a pointer to a protoent structure. The return value points to data that is overwritten by subsequent calls returning the same data structure.
If unsuccessful, getprotobynumber() returns a NULL pointer, indicating an error or End Of File (EOF).