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<HTML><HEAD><TITLE>NETBOOK - Code Sample 30_1</TITLE></HEAD><BODY BGCOLOR="#FFFFFF"><P><TABLE BORDER="0" CELLPADDING="5" CELLSPACING="0" WIDTH="600"><TR> <TD WIDTH="112" VALIGN="TOP" BGCOLOR="#759AC4" CELLPADDING="0"><img src="../pgmatrls/sidebar.gif" width="112" height="410" usemap="#sidebar" ismap alt="" border="0" ><map name="sidebar"><area shape="rect" coords="0,325,100,364" href="../othrpags/page22.htm" ><area shape="rect" coords="0,287,100,326" href="../othrpags/page17.htm" ><area shape="rect" coords="0,248,100,287" href="../othrpags/page18.htm" ><area shape="rect" coords="0,364,100,404" href="../othrpags/code.htm" ><area shape="rect" coords="0,210,100,248" href="../othrpags/page15.htm" ><area shape="rect" coords="0,170,100,210" href="../othrpags/page03.htm" ><area shape="rect" coords="0,132,100,170" href="../othrpags/page10.htm" ><area shape="rect" coords="0,93,100,132" href="../index.htm" ><AREA SHAPE="DEFAULT" NOHREF></map> </TD><TD WIDTH="420" VALIGN="TOP" BGCOLOR="#FFFFFF"><CENTER><H1>Code Sample 30_1</H1></CENTER><PRE>/* client.c - code for example client program that uses TCP */#ifndef unix#define WIN32#include <windows.h>#include <winsock.h>#else#define closesocket close#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <netdb.h>#endif#include <stdio.h>#include <string.h>#define PROTOPORT 5193 /* default protocol port number */extern int errno;char localhost[] = "localhost"; /* default host name *//*------------------------------------------------------------------------ * Program: client * * Purpose: allocate a socket, connect to a server, and print all output * * Syntax: client [ host [port] ] * * host - name of a computer on which server is executing * port - protocol port number server is using * * Note: Both arguments are optional. If no host name is specified, * the client uses "localhost"; if no protocol port is * specified, the client uses the default given by PROTOPORT. * *------------------------------------------------------------------------ */main(argc, argv)int argc;char *argv[];{ struct hostent *ptrh; /* pointer to a host table entry */ struct protoent *ptrp; /* pointer to a protocol table entry */ struct sockaddr_in sad; /* structure to hold an IP address */ int sd; /* socket descriptor */ int port; /* protocol port number */ char *host; /* pointer to host name */ int n; /* number of characters read */ char buf[1000]; /* buffer for data from the server */#ifdef WIN32 WSADATA wsaData; WSAStartup(0x0101, &wsaData);#endif memset((char *)&sad,0,sizeof(sad)); /* clear sockaddr structure */ sad.sin_family = AF_INET; /* set family to Internet */ /* Check command-line argument for protocol port and extract */ /* port number if one is specified. Otherwise, use the default */ /* port value given by constant PROTOPORT */ if (argc > 2) { /* if protocol port specified */ port = atoi(argv[2]); /* convert to binary */ } else { port = PROTOPORT; /* use default port number */ } if (port > 0) /* test for legal value */ sad.sin_port = htons((u_short)port); else { /* print error message and exit */ fprintf(stderr,"bad port number %s\n",argv[2]); exit(1); } /* Check host argument and assign host name. */ if (argc > 1) { host = argv[1]; /* if host argument specified */ } else { host = localhost; } /* Convert host name to equivalent IP address and copy to sad. */ ptrh = gethostbyname(host); if ( ((char *)ptrh) == NULL ) { fprintf(stderr,"invalid host: %s\n", host); exit(1); } memcpy(&sad.sin_addr, ptrh->h_addr, ptrh->h_length); /* Map TCP transport protocol name to protocol number. */ if ( ((int)(ptrp = getprotobyname("tcp"))) == 0) { fprintf(stderr, "cannot map \"tcp\" to protocol number"); exit(1); } /* Create a socket. */ sd = socket(PF_INET, SOCK_STREAM, ptrp->p_proto); if (sd < 0) { fprintf(stderr, "socket creation failed\n"); exit(1); } /* Connect the socket to the specified server. */ if (connect(sd, (struct sockaddr *)&sad, sizeof(sad)) < 0) { fprintf(stderr,"connect failed\n"); exit(1); } /* Repeatedly read data from socket and write to user's screen. */ n = recv(sd, buf, sizeof(buf), 0); while (n > 0) { write(1,buf,n); n = recv(sd, buf, sizeof(buf), 0); } /* Close the socket. */ closesocket(sd); /* Terminate the client program gracefully. */ exit(0);}</PRE><p><p><p><HR WIDTH=89% ALIGN=CENTER SIZE=2><center><h2>Item information</h2></center><p><TABLE CELLSPACING="0"><TD ALIGN="LEFT" VALIGN="TOP">Caption:</TD><TD ALIGN="LEFT">Code sample for client in section 30.6</TD><TR><TD ALIGN="LEFT">Code sample:</TD><TD ALIGN="LEFT">30_1</td><tr><TD ALIGN="LEFT">Type:</TD><TD ALIGN="LEFT">code sample</TD><TR><TD ALIGN="LEFT">Item:</TD><TD ALIGN="LEFT"><A HREF="./code30_1.txt">Code sample 30_1</A> without caption</TD><TR><TD ALIGN="LEFT">Keywords:</TD><TD ALIGN="LEFT">client, client code</TR></TABLE></tr></TABLE></BODY></HTML>⌨️ 快捷键说明
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