Midterm ex1

Please a design a simple calculator client and server such that the client sends an expression (e.g."123+456), which contains two operands and an operator, to the server. After received the expression, the server replies the caculating result to the client. Note that, the operands are 3-digit integer, the operator is in {+,-,*,/,%}, the expression is inputted from the keyboard, and the caculating result should be shown on the console of the client.

//---------------------------------------------------------------------------------------------
//tcpcli01.c
#include　"unp.h"

void　inexp(FILE *fp, int sockfd)
{
　char sendline[MAXLINE], recvline[MAXLINE];

　do {
　　printf("Please enter an expression (e.g. 123+456):\n");
　　if (Fgets(sendline, MAXLINE, fp) != NULL) {
　　　Writen(sockfd, sendline, strlen(sendline));
　　　if (Readline(sockfd, recvline, MAXLINE) == 0)
　　　　err_quit("inexp: server terminated prematurely");
　　　Fputs(recvline, stdout);
　　}
　} while (strlen(recvline)>10);
}

int　main(int argc, char **argv)
{
　int sockfd;
　struct sockaddr_in servaddr;

　if (argc != 2)
　　err_quit("usage: tcpcli ");

　sockfd = Socket(AF_INET, SOCK_STREAM, 0);

　bzero(&servaddr, sizeof(servaddr));
　servaddr.sin_family = AF_INET;
　servaddr.sin_port = htons(SERV_PORT);
　Inet_pton(AF_INET, argv[1], &servaddr.sin_addr);

　Connect(sockfd, (SA *) &servaddr, sizeof(servaddr));

　inexp(stdin, sockfd); /* do it all */

　exit(0);
}
//---------------------------------------------------------------------------------------------


//---------------------------------------------------------------------------------------------
//tcpserv01.c
#include "unp.h"

void　retrt(int sockfd)
{
　char buf[MAXLINE], rep[MAXLINE], op;
　int a, b;
　int success=0;

　do
　{
　　a=b=0;
　　if (read(sockfd, buf, MAXLINE)>0)
　　{
　　　printf("Received expression: %s\n",buf);
　　　if (sscanf(buf, "%d%c%d",&a, &op, &b)!=3)
　　　　snprintf(rep, sizeof(rep), "Invalid input: %s\n", buf);
　　　else if (a>=100 && a<=999 && b>=100 && b<=999)
　　　{
　　　　switch(op)
　　　　{
　　　　　case '+': snprintf(rep, sizeof(rep), "%d\n", a+b); success=1;
　　　　　break;
　　　　　case '-': snprintf(rep, sizeof(rep), "%d\n", a-b); success=1;
　　　　　break;
　　　　　case '*': snprintf(rep, sizeof(rep), "%d\n", a*b); success=1;
　　　　　break;
　　　　　case '/': snprintf(rep, sizeof(rep), "%d\n", a/b); success=1;
　　　　　break;
　　　　　case '%': snprintf(rep, sizeof(rep), "%d\n", a%b); success=1;
　　　　　break;
　　　　　default: snprintf(rep, sizeof(rep), "Invalid operator: %c\n", op);
　　　　}
　　　}
　　　else snprintf(rep, sizeof(rep), "Invalid number: %d or %d\n", a, b);
　　　Writen(sockfd, rep, strlen(rep));
　　}
　} while(success==0);
}

int　main(int argc, char **argv)
{
　int listenfd, connfd;
　struct sockaddr_in servaddr;
　listenfd = Socket(AF_INET, SOCK_STREAM, 0);

　bzero(&servaddr, sizeof(servaddr));
　servaddr.sin_family = AF_INET;
　servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
　servaddr.sin_port = htons(SERV_PORT);

　Bind(listenfd, (SA *) &servaddr, sizeof(servaddr));

　Listen(listenfd, LISTENQ);

　for ( ; ; ) {
　　connfd = Accept(listenfd, (SA *) NULL, NULL);
　　retrt(connfd); /* process the request */
　　Close(connfd);
　}
}
//---------------------------------------------------------------------------------------------