#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>

int main()
{
    int sockfd;
    int len;
    struct sockaddr_in address;
    int result;
    char ch = 'A';
    
    //Create a socket for the client
    sockfd = socket(AF_INET,SOCK_STREAM,0);
    //Name the socket,as agreed with the server
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = inet_addr("127.0.0.1");
    address.sin_port = 9734;
    len = sizeof(address);

    result = connect(sockfd,(struct sockaddr *)&address,len);
    if(result == -1)
    {
        perror("oops:client");
        exit(1);
    }

    write(sockfd, &ch, 1);
    read(sockfd, &ch, 1);
    printf("char from server = %c\n", ch);
    close(sockfd);
    return 0;
}

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>

int main()
{

    int server_sockfd,client_sockfd;
    socklen_t server_len,client_len;
    struct sockaddr_in server_address;
    struct sockaddr_in client_address;

    server_sockfd = socket(AF_INET, SOCK_STREAM, 0);
    server_address.sin_family = AF_INET;
    server_address.sin_addr.s_addr = inet_addr("127.0.0.1");
    server_address.sin_port = 9734;
    server_len = sizeof(server_address);
    bind(server_sockfd, (struct sockaddr *)&server_address, server_len);

    listen(server_sockfd,5);
    while(1)
    {
        char ch;
        printf("server waiting\n");

        client_len = sizeof(client_address);
        client_sockfd = accept(server_sockfd,(struct sockaddr *)&client_address,&client_len);
        read(client_sockfd,&ch,1);
        ch++;
        write(client_sockfd,&ch,1);

        close(client_sockfd);
    }
    return 0;
}