htonl( ), htons( ), ntohl( ), and ntohs( ) convert short (16-bit) and long (32-bit) quantities between network byte order and host byte order.

These routines are most often used in conjunction with Internet addresses and ports.

unsigned long htonl(hostlong)
  unsigned long hostlong;

unsigned short htons(hostshort) 
  unsigned short hostshort; 

unsigned long ntohl(netlong) 
  unsigned long netlong; 

unsigned short ntohs(netshort) 
  unsigned short netshort;

Requirements