Linux下的简单socket编程示例

/* * The Socket Client * example: client 192.168.0.2 6777 * */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> //#include <sys/types.h> #include <sys/socket.h> //#include <netinet/in.h> #include <netdb.h> void error(const char * msg) { perror(msg); exit(0); } // gets safe edition void gets_s(char *s,int n) { register int c; register char *cs; cs=s; while(--n>0 && (c=getc(stdin))!=EOF && c!='\n') *cs++=c; *cs='\0'; if((c==EOF && cs==s) ||(c=='\n' && cs==s)) s = NULL; } int main(int argc, char *argv[]) { int sockfd, portno, n; char buf[64]; struct sockaddr_in serv_addr; struct hostent *host; if (argc < 3) { fprintf(stderr, "usage %s hostname port\n", argv[0]); exit(0); } // Get server entry host = gethostbyname(argv[1]); if (host == NULL) { fprintf(stderr, "ERROR, no such host\n"); } // Get the socket portno = atoi(argv[2]); sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd < 0) { error("ERROR opening socket"); } printf("Created socket successfully! No: %d\n", sockfd); // Initialize socketaddr_in bzero((struct sockaddr_in *) &serv_addr, sizeof(serv_addr)); serv_addr.sin_family = AF_INET; bcopy((char *) host->h_addr, (char *) &serv_addr.sin_addr.s_addr, host->h_length); //inet_aton(host->h_addr_list[0], &serv_addr.sin_addr.s_addr); //serv_addr.sin_addr.s_addr = INADDR_ANY; serv_addr.sin_port = htons(portno); // connect printf("Connecting...\n"); if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr))) { error("ERROR on connecting"); } printf("Connected successfully.\n"); // input printf("Please enter the message:"); bzero(buf, 64); gets_s(buf, 64); printf("Writing...\n"); n = write(sockfd, buf, 64); if (n < 0) error("ERROR on reading"); printf("Your text is here:\n%s\n", buf); close(sockfd); printf("\nClosed!\n"); return 0; }