Notes

#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 portn", 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 hostn");
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); //Read Server String
if (n < 0)
error("ERROR reading from socket");
printf("Server - %sn",buffer);
scanf("%d" , &num1); //Enter No 1
write(sockfd, &num1, sizeof(int)); //Send No 1 to Server



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



bzero(buffer,256);
n = read(sockfd,buffer,255); //Read Server String
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 : %dn" , ans); //Get Answer from server

if(choice != 5)
goto S;

Q: printf("You chose to exit, Thank You so much.");




close(sockfd);
return 0;
}
/*
gcc Server.c -o Server
./Server 4562
gcc client.c -o client
./client 192.168.244.139 4562
*/

#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 providedn");
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 : %dn" , 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 : %dn" , num2);


n = write(newsockfd,"Enter your choice : n1.Additionn2.Subtractionn3.Multiplicationn4.Divisionn5.Exitn",strlen("Enter your choice : n1.Additionn2.Subtractionn3.Multiplicationn4.Divisionn5.Exitn")); //Ask for choice
if (n < 0) error("ERROR writing to socket");
read(newsockfd, &choice, sizeof(int)); //Read choice
printf("Client - Choice is : %dn" , 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;
}