1.
#include<iostream>
#include<string.h>
using namespace std;
char stack[6][30];
int top=-1;
void push()
{ int j;
	if(top==5)
	cout<<"stack is full";                                     //to check whether stack is full or not
	else
	{
		char x[30];
		cout<<"Enter layer name: \n";
		cin>>x;
		top++;
		for(j=0;x[j]!='\0';j++)
		{
		stack[top][j]=x[j];                                  //Layer names are pushed into the stack
	}
	}
}
void pop(char st[30])
{int j;
char x[30];
	if(top==-1)
	cout<<"stack is empty";                              //to check whether stack is empty or not
	else
	{
		for(j=0;stack[top][j]!='\0';j++)
		{
		x[j]=stack[top][j];                         //popping out the layer names from the stack
	}
		top--;
	cout<<x;
	for(j=0;j<30;j++)
	{
		x[j]='\0';
	}
			cout<<" "<<st<<"\n";
		cout<<"\n\n";
	}
}
void display()
{
	char s[30];
cout<<"Enter the string: ";
cin>>s;
cout<<"-----------\n";
cout<<"TRANSMITTER\n";
cout<<"-----------\n\n";
	cout<<stack[0]<<"\n\n";
	for(int i=1;i<=top;i++)
	{
	cout<<stack[i];                                //Printing the stack
	cout<<" "<<s<<"\n";
	cout<<"\n\n";
}
cout<<"MESSAGE ENTERED INTO PHYSICAL LAYER AND TRANSMITTED.\n\n";
cout<<"-----------\n";
	cout<<"RECEIVER\n";
		cout<<"-----------\n\n";
cout<<"MESSAGE ENTERED INTO PHYSICAL LAYER.\n";
	for(int i=top;i>=1;i--)
	pop(s);
	cout<<stack[0]<<"\n\n";                                    //Printing the first element of the stack
}
int main()
{
int i;
		for(i=0;i<6;i++)
		push();
			cout<<"--------------------\n\n";
			display();
			return 0;

}

2. a) Bit stuffing
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
	inti,j,count=0,nl;
	charstr[100];
	//clrscr();
	printf("enter the bit string:  ");
	gets(str);
	for (i=0;i<strlen(str);i++) {
		count=0;
		                                       //the following code search the six ones in given string
		for (j=i;j<=(i+5);j++) {
			if(str[j]=='1') {
				count++;
			}
		}
		//if there is six ones then folling code execute to bit stuffing after five ones
		if(count==6) {
			nl=strlen(str)+2;
			for (;nl>=(i+5);nl--) {
				str[nl]=str[nl-1];
			}
			str[i+5]='0';
			i=i+7;
		}
	}
	puts(str);
	getch();
}


b) Byte stuffing
/*Implement the DataLinklayer framing methods such as Character
stuffing*/
#include<stdio.h>
#include<string.h>
#include<conio.h>
void main()
{
intj,l,m,c,k;
char a[50],b[50];
printf("Enter the string: ");
scanf("%s",a);
strcpy(b,"DLESTX");          //Copy DLESTX in b
m=strlen(a);                         //Length of a is stored in m
for(j=0;j<m;)
{
if(a[j]=='d')
{
if(a[j+1]=='l')
{
if(a[j+2]=='e')
{
c=j+2;
for(l=0;l<3;l++)
{
for(k=m;k>c;k--)
{
a[k]=a[k-1];
}
m++;
a[m]=NULL;
c+=1;
}
a[j+3]='d';
a[j+4]='l';
a[j+5]='e';
a[m]=NULL;
j+=5;
}
}
}
j++;
}
strcat(b,a);
strcat(b,"DLEETX");
printf("\n%s",b);
printf("\nReceiver side:");       //Reciever side
m=strlen(a);
for(j=0;j<m;)
{
if(a[j]=='d')
{
if(a[j+1]=='l')
{
if(a[j+2]=='e')
{
c=j;
for(l=0;l<3;l++)
{
for(k=c;k<m;k++)
a[k]=a[k+1];
}
c++;
}
j=c;
}
}
j++;
}
printf("\n%s",a);
getch();
}

c) To implement Character Count
Program-
#include <stdio.h>
#include <string.h>
int main(){
int size;
int total=0;
int i=1;
intj,k=0;
intfsize;
printf("Enter the no. of characters: ");                         //Entering number of characters
scanf("%d",&size);
charstr[size];
printf("\nEnter the characters: ");
scanf("%s",str);
while(k<size)
{
printf("Enter the frame %d size: ",i);
scanf("%d",&fsize);
char frame[fsize+1];                                                   //Incrementing frame size
i++;
total+=fsize;
frame[0]=(char)(fsize+48);
for(j=1;j<fsize;j++)
{
if(k<size)
{
printf("%c\n",str[k]);
frame[j]=str[k];
k++;
}
}
frame[fsize]='\0';
printf("%s\n",frame);
}
return 0;
}

3. CRC
#include<stdlib.h>
#include<conio.h>
#include<stdio.h>
void main()
{
inti,j,n,g,a,arr[20],gen[20],b[20],q[20],s;

printf("Transmitter side:");
printf("\nEnter no. of data bits:");                   //Number of data bits are entered
scanf("%d",&n);
printf("Enter data:");
for(i=0;i<n;i++)
scanf("%d",&arr[i]);                                  //Data is stored in the form of an array

printf("Enter size of generator:");
scanf("%d",&g);
do{
printf("Enter generator:");                      //Divisor value is entered by the user
for(j=0;j<g;j++)
scanf("%d",&gen[j]);

}
while(gen[0]!=1);                              //Converting into Matrix
printf("\n\tThe generator matrix:");
for(j=0;j<g;j++)
printf("%d",gen[j]);

a=n+(g-1);
printf("\n\tThe appended matrix is:");                //Displaying appended matrix
for(i=0;i< j;++i)
arr[n+i]=0;

for(i=0;i< a;++i)

printf("%d",arr[i]);

for(i=0;i< n;++i)
q[i]= arr[i];

for(i=0;i< n;++i)
{
if(arr[i]==0)
{
for(j=i;j<g+i;++j)
arr[j] = arr[j]^0;
}
else                                           //Performing Division
{
arr[i] = arr[i]^gen[0];
arr[i+1]=arr[i+1]^gen[1];
arr[i+2]=arr[i+2]^gen[2];
arr[i+3]=arr[i+3]^gen[3];
}
}
printf("\n\tThe CRC is :");
for(i=n;i< a;++i)
printf("%d",arr[i]);
s=n+a;
for(i=n;i<s;i++)
q[i]=arr[i];
printf("\n");
for(i=0;i<a;i++)
printf("%d",q[i]);
getch();
}

4. Checksum Calculation

Code:
#include<stdio.h>
#include<math.h>
int sender(int b[10],int k)
{
intchecksum,sum=0,i;
printf("\n****SENDER****\n");
for(i=0;i<k;i++)
sum+=b[i];                                      //Performing sum on each value
printf("SUM IS: %d",sum);
checksum=~sum;
printf("\nSENDER's CHECKSUM IS:%d",checksum);
return checksum;                            //returning value of checksum
}
int receiver(int c[10],intk,intscheck)
{ intchecksum,sum=0,i;
printf("\n\n****RECEIVER****\n");
for(i=0;i<k;i++)
sum+=c[i];
printf(" RECEIVER SUM IS:%d",sum);
sum=sum+scheck;
checksum=~sum;
printf("\nRECEIVER's CHECKSUM IS:%d",checksum);
return checksum;
}
int main()
{
int a[10],i,m,scheck,rcheck;
printf("\nENTER SIZE OF THE STRING:");
scanf("%d",&m);
printf("\nENTER THE ELEMENTS OF THE ARRAY:");
for(i=0;i<m;i++)
scanf("%d",&a[i]);
scheck=sender(a,m);
rcheck=receiver(a,m,scheck);
if(rcheck==0)
printf("\n\nNO ERROR IN TRANSMISSION\n\n");
else
printf("\n\nERROR DETECTED");
return 0;
}

5. Hamming Code
Code:
#include<stdio.h>
void main() {
int data[7],rec[7],i,c1,c2,c3,c;
printf("this works for message of 4bits in size \nenter message bit one by
one: ");
scanf("%d%d%d%d",&data[0],&data[1],&data[2],&data[4]);     //data is stored
data[6]=data[0]^data[2]^data[4];
data[5]=data[0]^data[1]^data[4];
data[3]=data[0]^data[1]^data[2];
printf("\nthe encoded bits are given below: \n");
for (i=0;i<7;i++) {
printf("%d ",data[i]);
}
printf("\nenter the received data bits one by one: ");
for (i=0;i<7;i++) {
scanf("%d",&rec[i]);
}
c1=rec[6]^rec[4]^rec[2]^rec[0];
c2=rec[5]^rec[4]^rec[1]^rec[0];
c3=rec[3]^rec[2]^rec[1]^rec[0];
c=c3*4+c2*2+c1 ;
if(c==0) {
printf("\ncongratulations there is no error: ");
} else {
printf("\nerror on the postion: %d\nthe correct message is \n",c);
if(rec[7-c]==0)
rec[7-c]=1; else
rec[7-c]=0;
for (i=0;i<7;i++) {
printf("%d ",rec[i]);                             //Printing the correct message
}
}
}

6.Simulation of Sliding protocol
PROGRAM:
#include<stdio.h>
int main()
{
char sender[50],receiver[50],temp[50];
inti,winsize;

printf("\n ENTER THE WINDOWS SIZE : ");
scanf("%d",&winsize);
printf("\n SENDER WINDOW IS EXPANDED TO STORE MESSAGE OR WINDOW \n");
printf("\n ENTER THE DATA TO BE SENT: ");
fflush(stdin);
gets(sender);
for(i=0;i<winsize;i++)
temp[i]=  receiver[i];
receiver[i]=sender[i];
receiver[i]=temp[i];
printf("\n MESSAGE SEND BY THE SENDER:\n");
puts(sender);
printf("\n WINDOW SIZE OF RECEIVER IS EXPANDED\n");
printf("\n ACKNOWLEDGEMENT FROM RECEIVER \n");
for(i=0;i<winsize;i++);
printf("\n ACK:%d",i);
printf("\n MESSAGE RECEIVED BY RECEIVER IS : ");
puts(receiver);
printf("\n WINDOW SIZE OF RECEIVER IS SHRINKED \n");

}


7. Chat application using TCP/IP


Code:
// Server Program - Communicating to single client multiple number of times
#include<stdio.h>
#include<netinet/in.h>
#include<netdb.h>
#include<string.h>
#define SERV_TCP_PORT 5035
int main(int argc,char**argv)
{
int sockfd,newsockfd,clength;
struct sockaddr_in serv_addr,cli_addr;
char buffer[4096];
                                                                                             //creating a socket
sockfd=socket(AF_INET,SOCK_STREAM,0);
serv_addr.sin_family=AF_INET;
serv_addr.sin_addr.s_addr=INADDR_ANY;
serv_addr.sin_port=htons(SERV_TCP_PORT);
printf("\nStart");
                                                                               //bind the socket to port address and any local interface
bind(sockfd,(struct sockaddr*)&serv_addr,sizeof(serv_addr));
printf("\nListening...");
printf("\n");
listen(sockfd,5);
clength=sizeof(cli_addr);
newsockfd=accept(sockfd,(struct sockaddr*)&cli_addr,&clength);
//newsockfd=accept(sockfd,(struct sockaddr*)NULL,NULL);
printf("\nAccepted");
printf("\n");
while(1)
{
bzero(buffer,4096);
read(newsockfd,buffer,4096);
printf("\nClient message:%s",buffer);
write(newsockfd,buffer,strlen(buffer)+1);
printf("\n");
}
//close(sockfd);
//return 0;
}


Client Side:
Client Program - Multiple communications to server
#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<netdb.h>
#define SERV_TCP_PORT 5035
int main(int argc,char*argv[])
{
int sockfd;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[4096];
int k=5,cnt=0;
sockfd=socket(AF_INET,SOCK_STREAM,0);
serv_addr.sin_family=AF_INET;
serv_addr.sin_addr.s_addr=inet_addr("127.0.0.1");
serv_addr.sin_port=htons(SERV_TCP_PORT);
printf("\nReady for sending...");
connect(sockfd,(struct sockaddr*)&serv_addr,sizeof(serv_addr));
while(cnt <= k)
{
printf("\nEnter the message to send\n");
printf("\nClient: ");
fgets(buffer,4096,stdin);
write(sockfd,buffer,4096);
printf("Serverecho:%s",buffer);
printf("\n");
cnt++;
}
close(sockfd);
return 0;

8. TCP client/server application for transferring a text file from client to server

PROGRAM:
Server:
#include<stdio.h>
#include<sys/types.h>
#include<string.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<unistd.h>
#define SA structsockaddr
#define LISTENQ 5
int main(intargc,char**argv)
{
intfd,sockfd,listenfd,connfd;
pid_tchildpid;
socklen_t client;
structsockaddr_inservaddr,cliaddr;
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(atoi(argv[1]));
bind(listenfd,(SA*)&servaddr,sizeof(servaddr));
listen(listenfd,LISTENQ);
client=sizeof(cliaddr);
connfd=accept(listenfd,(SA*)&cliaddr,&client);
char buffer[100];
FILE *fp;
read(connfd,buffer,100);
fp=fopen("add1.txt","w");
fprintf(fp,"%s",buffer);
printf("the file was received successfully");
printf("the new file created is add1.txt");
}
Client :
#include<arpa/inet.h>
#include<unistd.h>
#define SA structsockaddr
int main(intargc,char**argv)
{
intsockfd;
charfname[25];
intlen;
structsockaddr_inservaddr,cliaddr;
sockfd=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(atoi(argv[1]));
inet_pton(AF_INET,argv[1],&servaddr.sin_addr);
connect(sockfd,(SA*)&servaddr,sizeof(servaddr));
char buffer[100];
FILE *f;
f=fopen("add.txt","r");
fscanf(f,"%s",buffer);
write(sockfd,buffer,100);
printf("the file was sent successfully");
}

9.  TCP based server program to authenticate the client’s Username and Password.

PROGRAM:
Server:
#include (stdio.h)
#include (stdlib.h)
#include (unistd.h)
#include (errno.h)
#include (string.h)
#include (netdb.h)
#include (sys/types.h)
#include (netinet/in.h)
#include (sys/socket.h)
#include (arpa/inet.h)
int main(intargc, char *argv[])
{
int sock_des,port,n1,n2,s1,s2;
char buffer1[100],buffer2[100],buffer3[100],buffer4[100];
intlength,new_des;
structsockaddr_inserver_addr,client_addr;
bzero(buffer3,sizeof(buffer3));
printf(“\n Input Authentic Username :\n”);
scanf(“%s”,buffer3);
bzero(buffer4,sizeof(buffer4));
printf(“\n Input Authentic Password :\n”);
scanf(“%s”,buffer4);
if(argc!=2)
{
printf(“Usage: ./server port\n”);
exit(1);
}
port= atoi(argv[1]);
if((sock_des=socket(AF_INET,SOCK_STREAM,0))==-1)
{
perror(“socket”);
exit(1);
}
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(port);
server_addr.sin_addr.s_addr= htonl(INADDR_ANY);
if (bind(sock_des,(conststructsockaddr *)&server_addr,sizeof(structsockaddr))==-1)
{
perror(“bind”);
exit(1);
}
if( listen(sock_des,5)==-1)
{
perror(“listen”);
exit(1);
}
printf(“Server is listening at port %d \n”, port);
while(1)
{
if((new_des=accept(sock_des,(structsockaddr *)&client_addr,&length))==-1)
{
perror(“accept”);
exit(1);
}
bzero(buffer1,sizeof(buffer1));
n1=read(new_des,buffer1,sizeof(buffer1));
buffer1[n1]=’null character’;
if((s1=strcmp(buffer1,buffer3))==0)
{
write(new_des,”UsernameMatch!Enter Password”,30);
printf(“Username Match !!!\n”);
bzero(buffer2,sizeof(buffer2));
n2=read(new_des,buffer2,sizeof(buffer2));
buffer2[n2]=’null character’;
if((s2=strcmp(buffer2,buffer4))==0)
{
write(new_des,”Password Match”,15);
printf(“Password Match !!!\n”);
}
else
{
write(new_des,”Password NOT Match”,19);
printf(“Password NOT Match !!!\n”);
}
}
else
{
write(new_des,”Username Not Match”,19);
printf(“Username Not Match !!!\n”);
}
close(new_des);
}
}
Client:
#include (stdio.h)

#include (stdlib.h)

#include (unistd.h)

#include (errno.h)

#include (string.h)

#include (netdb.h)

#include (sys/types.h)

#include (netinet/in.h)

#include (sys/socket.h)

#include (arpa/inet.h)

int main(intargc,char *argv[])

{

intsock_des,port,n;

structhostent *host;

char buffer1[100],buffer2[100],buffer3[100],buffer4[100];

structsockaddr_inserver_addr;

if(argc!=3)

{

printf(“Usage: ./client hostname port\n”);

exit(1);

}

if((host=gethostbyname(argv[1]))==NULL)

{

printf(“Unknown Host\n”);

exit(1);

}

port = atoi(argv[2]);

if((sock_des=socket(AF_INET,SOCK_STREAM,0))==-1)

{

perror(“socket”);

exit(1);

}

server_addr.sin_family = AF_INET;

server_addr.sin_port = htons(port);

server_addr.sin_addr = *((structin_addr *)host->h_addr);

if(connect(sock_des,(structsockaddr *)&server_addr,sizeof(structsockaddr))==-1)

{

perror(“connect”);

exit(1);

}

bzero(buffer1,sizeof(buffer1));

printf(“Enter the Username :\n”);

scanf(“%s”,buffer1);

write(sock_des,buffer1,sizeof(buffer1));

bzero(buffer4,sizeof(buffer4));

n=read(sock_des,buffer4,sizeof(buffer4));

buffer4[n]=’null character’;

printf(“Server Sent : %s\n”, buffer4);

bzero(buffer2,sizeof(buffer2));

printf(“Enter the Password :\n”);

scanf(“%s”,buffer2);

write(sock_des,buffer2,sizeof(buffer2));

bzero(buffer3,sizeof(buffer3));

n=read(sock_des,buffer3,sizeof(buffer3));

buffer3[n]=’null character’;

printf(“Server Sent : %s\n”, buffer3);

close(sock_des);

}
Download as text

10.  Implement a message transfer from client to server process using UDP.

/************* UDP SERVER CODE *******************/

#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <stdlib.h>

int main(){
  int udpSocket, nBytes;
  char buffer[1024];
  struct sockaddr_in serverAddr, clientAddr;
  struct sockaddr_storage serverStorage;
  socklen_t addr_size, client_addr_size;
  int i;

  /*Create UDP socket*/
  udpSocket = socket(PF_INET, SOCK_DGRAM, 0);

  /*Configure settings in address struct*/
  serverAddr.sin_family = AF_INET;
  serverAddr.sin_port = htons(7891);
  serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
  memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);

  /*Bind socket with address struct*/
  bind(udpSocket, (struct sockaddr *) &serverAddr, sizeof(serverAddr));

  /*Initialize size variable to be used later on*/
  addr_size = sizeof serverStorage;

  while(1){
    /* Try to receive any incoming UDP datagram. Address and port of
      requesting client will be stored on serverStorage variable */
    nBytes = recvfrom(udpSocket,buffer,1024,0,(struct sockaddr *)&serverStorage, &addr_size);

    /*Convert message received to uppercase*/
    for(i=0;i<nBytes-1;i++)
      buffer[i] = toupper(buffer[i]);

    /*Send uppercase message back to client, using serverStorage as the address*/
    sendto(udpSocket,buffer,nBytes,0,(struct sockaddr *)&serverStorage,addr_size);
  }

  return 0;

/************* UDP CLIENT CODE *******************/

#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>

int main(){
  int clientSocket, portNum, nBytes;
  char buffer[1024];
  struct sockaddr_in serverAddr;
  socklen_t addr_size;

  /*Create UDP socket*/
  clientSocket = socket(PF_INET, SOCK_DGRAM, 0);

  /*Configure settings in address struct*/
  serverAddr.sin_family = AF_INET;
  serverAddr.sin_port = htons(7891);
  serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
  memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);

  /*Initialize size variable to be used later on*/
  addr_size = sizeof serverAddr;

  while(1){
    printf("Type a sentence to send to server:\n");
    fgets(buffer,1024,stdin);
    printf("You typed: %s",buffer);

    nBytes = strlen(buffer) + 1;

    /*Send message to server*/
    sendto(clientSocket,buffer,nBytes,0,(struct sockaddr *)&serverAddr,addr_size);

    /*Receive message from server*/
                nBytes = recvfrom(clientSocket,buffer,1024,0,NULL, NULL);

    printf("Received from server: %s\n",buffer);

  }

  return 0;
}


11. To write a program for UDP echo client server.
ALGORITHM:
SERVER:
    STEP 1: Start
    STEP 2: Declare the variables for the socket
    STEP 3: Specify the family, protocol, IP address and port number
    STEP 4: Create a socket using socket() function
    STEP 5: Bind the IP address and Port number
    STEP 6: Listen and accept the client’s request for the connection
    STEP 7: Read and Display the client’s message
    STEP 8: Stop
CLIENT:
    STEP 1: Start
    STEP 2: Declare the variables for the socket
    STEP 3:  Specify the family, protocol, IP address and port number
    STEP 4: Create a socket using socket() function
    STEP 5: Call the connect() function
    STEP 6: Read the input message
    STEP 7: Send the input message to the server
    STEP 8: Display the server’s echo
    STEP 9: Close the socket
    STEP 10: Stop

SOURCE CODE:
SERVER:
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<unistd.h>
#include<netdb.h>
#include<stdio.h>
#include<string.h>
#include<arpa/inet.h>
#define MAXLINE 1024
int main(int argc,char **argv)
{
int sockfd;
int n;
socklen_t len;
char msg[1024];
struct sockaddr_in servaddr,cliaddr;
sockfd=socket(AF_INET,SOCK_DGRAM,0);
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family=AF_INET;
servaddr.sin_addr.s_addr=INADDR_ANY;
servaddr.sin_port=htons(5035);
printf("\n\n Binded");
bind(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr));
printf("\n\n Listening...");
for(;;)
{
      printf("\n ");
     len=sizeof(cliaddr);
     n=recvfrom(sockfd,msg,MAXLINE,0,(struct sockaddr*)&cliaddr,&len);
     printf("\n Client's Message : %s\n",msg);
     if(n<6)
        perror("send error");
     sendto(sockfd,msg,n,0,(struct sockaddr*)&cliaddr,len);
}
return 0;
}

CLIENT:
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<string.h>
#include<arpa/inet.h>
#include<string.h>
#include<arpa/inet.h>
#include<stdio.h>
#define MAXLINE 1024
int main(int argc,char* argv[])
{
int sockfd;
int n;
socklen_t len;
char sendline[1024],recvline[1024];
struct sockaddr_in servaddr;
strcpy(sendline,"");
printf("\n Enter the message : ");
scanf("%s",sendline);
sockfd=socket(AF_INET,SOCK_DGRAM,0);
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family=AF_INET;
servaddr.sin_addr.s_addr=inet_addr("127.0.0.1");
servaddr.sin_port=htons(5035);
connect(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr));
len=sizeof(servaddr);
sendto(sockfd,sendline,MAXLINE,0,(struct sockaddr*)&servaddr,len);
n=recvfrom(sockfd,recvline,MAXLINE,0,NULL,NULL);
recvline[n]=0;
printf("\n Server's Echo : %s\n\n",recvline);
return 0;
}