Calculator.txt

/* CALCULATOR:
SERVER:
Problem Statement: To implement client-server calculator.

	Server Side
	Please pass port no as command line argument
*/
#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 <ctype.h>


void error(const char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
     int sockfd, newsockfd, portno;
     socklen_t clilen;
     char buffer[1024];
     struct sockaddr_in serv_addr, cli_addr;
     int n;
     if (argc < 2) {
         fprintf(stderr,"ERROR, no port provided\n");
         exit(1);
     }
     sockfd = socket(AF_INET, SOCK_STREAM, 0);
     if (sockfd < 0) 
        error("ERROR opening socket");
     bzero((char *) &serv_addr, sizeof(serv_addr));
     portno = atoi(argv[1]);
     serv_addr.sin_family = AF_INET;
     serv_addr.sin_addr.s_addr = INADDR_ANY;
     serv_addr.sin_port = htons(portno);
     if (bind(sockfd, (struct sockaddr *) &serv_addr,
              sizeof(serv_addr)) < 0) 
              error("ERROR on binding");
     listen(sockfd,5);
     clilen = sizeof(cli_addr);
     newsockfd = accept(sockfd, 
                 (struct sockaddr *) &cli_addr, 
                 &clilen);
     if (newsockfd < 0) 
          error("ERROR on accept");
       
       
       
     int num1 , num2 , ans , choice;
 S:  n = write(newsockfd,"Enter Number 1 : ",strlen("Enter Number 1"));         //Ask for Number 1     
     if (n < 0) error("ERROR writing to socket");
     read(newsockfd, &num1, sizeof(int));					//Read No 1
     printf("Client - Number 1 is : %d\n" , num1);
          
          
     n = write(newsockfd,"Enter Number 2 : ",strlen("Enter Number 2"));         //Ask for Number 2    
     if (n < 0) error("ERROR writing to socket");
     read(newsockfd, &num2, sizeof(int));					//Read Number 2
     printf("Client - Number 2 is : %d\n" , num2);
     
     
     n = write(newsockfd,"Enter your choice : \n1.Addition\n2.Subtraction\n3.Multiplication\n4.Division\n5.Exit\n",strlen("Enter your choice : \n1.Addition\n2.Subtraction\n3.Multiplication\n4.Division\n5.Exit\n"));         //Ask for choice    
     if (n < 0) error("ERROR writing to socket");
     read(newsockfd, &choice, sizeof(int));					//Read choice
     printf("Client - Choice is : %d\n" , choice);	
     
     
      switch(choice)
     {
     	case 1:
     		ans = num1 + num2;
     		break;
     	case 2:
     		ans = num1 -num2;
     		break;
     	case 3:
     		ans = num1*num2;
     		break;
     	case 4:
     		ans = num1/num2;
     		break;
     	case 5 :
 		goto Q;
     		break;
     }
     
     write(newsockfd , &ans , sizeof(int));
     if(choice != 5)
     	goto S;
    
   Q:  close(newsockfd);
     close(sockfd);
     return 0; 
}


*/
CLIENT:
Please pass ip address and port no as command line arguments in the same sequence.
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 
#include<ctype.h>

void error(const char *msg)
{
    perror(msg);
    exit(0);
}

int main(int argc, char *argv[])
{
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;

    char buffer[1024];
    if (argc < 3)
    {
       fprintf(stderr,"usage %s hostname port\n", argv[0]);
       exit(0);
    }
    portno = atoi(argv[2]);
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) 
        error("ERROR opening socket");
    server = gethostbyname(argv[1]);
    if (server == NULL) {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
    }
    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr, 
         (char *)&serv_addr.sin_addr.s_addr,
         server->h_length);
    serv_addr.sin_port = htons(portno);
    if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) 
        error("ERROR connecting");
  
  
    int num1 ;
    int num2 ;
    int ans;
    int choice;
    
    
    
  S:bzero(buffer,256);						
    n = read(sockfd,buffer,255);				
    if (n < 0) 
         error("ERROR reading from socket");
    printf("Server - %s\n",buffer);
    scanf("%d" , &num1);						//Enter No 1
    write(sockfd, &num1, sizeof(int));     			

    bzero(buffer,256);					
    n = read(sockfd,buffer,255);				
    if (n < 0) 
         error("ERROR reading from socket");
    printf("Server - %s\n",buffer);
    scanf("%d" , &num2);			
    write(sockfd, &num2, sizeof(int));     //Send No 2 to Server
	
    bzero(buffer,256);						
    n = read(sockfd,buffer,255);
    if (n < 0) 
         error("ERROR reading from socket");
    printf("Server - %s",buffer);
    scanf("%d" , &choice);				//Enter choice
    write(sockfd, &choice, sizeof(int));     	//Send choice to Server

	if (choice == 5)
	goto Q;

    read(sockfd , &ans , sizeof(int));				//Read Answer from Server
    printf("Server - The answer is : %d\n" , ans); //Get Answer from server
	
    if(choice != 5)
    	goto S;
    	
Q:  printf("You chose to exit, Thank You so much.");
    
    close(sockfd);
    return 0;
}