Write a program for client server using point to point connection.

Aim :Write a program for client  server using point to point connection.

Client 
   
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <netdb.h>
    /* the port users will be connecting to */
    #define MYPORT 8888
    int main(int argc, char *argv[ ])
    {
    int sockfd;
   /* connector’s address information */
    struct sockaddr_in their_addr;
    struct hostent *he;
    int numbytes;
    /*i get the host info */
    he = gethostbyname(argv[1]);
        sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    /* host byte order */
    their_addr.sin_family = AF_INET;
    /* short, network byte order */
    printf("Using port: 8888\n");
    their_addr.sin_port = htons(MYPORT);
    their_addr.sin_addr = *((struct in_addr *)he->h_addr);
    /* zero the rest of the struct */
    memset(&(their_addr.sin_zero), '\0', 8);
    numbytes = sendto(sockfd, argv[2], strlen(argv[2]), 0, (struct sockaddr *)&their_addr,                sizeof(struct sockaddr));
if (close(sockfd) != 0)
printf("Your Messege is not sent...sorry\n");
else
printf("Your Messege is successfully sent.\n");
    return 0;
    }



Server

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define MYPORT 8888
#define MAXBUFLEN 500
int main(int argc, char *argv[])
{
     int sockfd;
    /* my address information */
     struct sockaddr_in my_addr;
   /* connector’s address information */
     struct sockaddr_in their_addr;
     int addr_len, numbytes;
     char buf[MAXBUFLEN];
     sockfd = socket(AF_INET, SOCK_DGRAM, 0);
     printf("Server-socket() sockfd is OK...\n");
    /* host byte order */
     my_addr.sin_family = AF_INET;
   /* short, network byte order */
     my_addr.sin_port = htons(MYPORT);
   /* automatically fill with my IP */
    my_addr.sin_addr.s_addr = INADDR_ANY;
   /* zero the rest of the struct */
    memset(&(my_addr.sin_zero), '\0', 8);
    bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr));
    addr_len = sizeof(struct sockaddr);
     numbytes = recvfrom(sockfd, buf, MAXBUFLEN-1, 0, (struct sockaddr *)&their_addr,   &addr_len);
     buf[numbytes] = '\0';
printf("THIS MSG SEND BY  CLIENT TO SERVER ::> \"%s\"\n", buf);
 close(sockfd);
 return 0;
 }

program to implement else if command

Aim: Write a program to implement else if command.

Program:

#include<stdio.h>

int main(int argc, char *argv[])

{

          int fd;

          char c;

          if(arg!=2)

          {

                   printf(“ERROR”);

                    fd=open(argv[1],O_RDONLY);

                   while((sk=READ(fd,&c,1))==1)

          }

          printf(“%c”,&c);

          sk=lseek(fd,1000,0)

          printf(“New seek value = %d”,sk);

}

}

Output:

cc seek.c

./a.out seek.c

#new seek value 1000

program for cat command

Aim: Write a program for cat command.

Program:

#include<stdio.h>

#include<fcntl.h>

#define buf 2048

int main(int argc, char *argv[])

{

          int fd;

          char buf1[buf];

          fd=open(argv[1],O_RDWR);

          read(fd,buf1,buf);

          printf(“%s”,buf1);

}

Output:

$ cc cat.c

$ ./a.out cat.txt