htons function in c

/************************************************************************ * File : htons-example.c * Author : Saurabh Gupta * Desc : Demonstrate htons function * htons example * host to network short * htons implementation * htons linux * Source : http://saurabhgupta0527.blogspot.com/2011/07/socket.html * Created : AM 08:14 05 October 2011 ***********************************************************************/ #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/socket.h> #include <sys/un.h> #include <netinet/in.h> #include <arpa/inet.h> /* * This saves lines of code later: */ static void displayError(const char *on_what) { perror(on_what); /* Report error */ exit(1); /* Exit Program */ } /* * This function accepts as input a socket * for which a socket address must be * determined for it. Then the address * is converted into a string and returned. * * If an error occurs, NULL is returned. */ char * sock_addr(int s,char *buf,size_t bufsiz) { int z; /* Status return code */ struct sockaddr_in adr_inet;/* AF_INET */ int len_inet; /* length */ /* * Obtain the address of the socket: */ len_inet = sizeof adr_inet; z = getsockname(s, (struct sockaddr *)&adr_inet, &len_inet); if ( z == -1 ) { return NULL; /* Failed */ } /* * Convert address into a string * form that can be displayed: */ snprintf(buf,bufsiz, "%s:%u", inet_ntoa(adr_inet.sin_addr), (unsigned)ntohs(adr_inet.sin_port)); return buf; } /* * Main Program: */ int main(int argc,char **argv,char **envp) { int z; /* Status return code */ int sck_inet; /* Socket */ struct sockaddr_in adr_inet;/* AF_INET */ int len_inet; /* length */ char buf[64]; /* Work buffer */ /* * Create an IPv4 Internet Socket: */ sck_inet = socket(AF_INET,SOCK_STREAM,0); if ( sck_inet == -1 ) { displayError("socket()"); } /* * Create an AF_INET address: * See the Usage of the htons function */ memset(&adr_inet,0,sizeof adr_inet); adr_inet.sin_family = AF_INET; adr_inet.sin_port = htons(9000); inet_aton ("127.0.0.24",&adr_inet.sin_addr); len_inet = sizeof adr_inet; /* * Now bind the address to the socket: */ z = bind(sck_inet, (struct sockaddr *)&adr_inet, len_inet); if ( z == -1 ) { displayError("bind()"); } /* * Now test our sock_addr() function: */ if ( !sock_addr(sck_inet,buf,sizeof buf)) { displayError("sock_addr()"); } printf("Address is'%s'\n" ,buf); close(sck_inet); return 0; } /* * OUTPUT * [sgupta@rhel55x86 htons]$ gcc htons-example.c -o htons-example [sgupta@rhel55x86 htons]$ ./htons-example Address is'127.0.0.24:9000' [sgupta@rhel55x86 htons]$ */See Also

1. htonl
2. ntohl
3. ntohs