/*
NAME: Amod Deshmukh
CLASS: TE A
ROLL NO: 16
ASSIGNMENT NO: 4
PROBLEM STATEMENT: Write a program using TCP socket for wired network for following
Say Hello to each other (chat): server side 
*/

#include<stdio.h>
#include<netinet/in.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netdb.h>
#include<stdlib.h>
#include<string.h>
#define MAX 80
#define PORT 43454
#define SA struct sockaddr
void func(int sockfd)
{
    char buff[MAX];
    int n;
    for(;;)
    {
        bzero(buff,MAX);
        read(sockfd,buff,sizeof(buff));
        printf("From client: %s\t To client : ",buff);
        bzero(buff,MAX);
        n=0;
        while((buff[n++]=getchar())!='\n');
            write(sockfd,buff,sizeof(buff));
        if(strncmp("exit",buff,4)==0)
        {
            printf("Server Exit...\n");
            break;
        }
    }
}
int main()
{
	int sockfd,connfd,len;
	struct sockaddr_in servaddr,cli;
	sockfd=socket(AF_INET,SOCK_STREAM,0);
	if(sockfd==-1)
	{
	 printf("socket creation failed...\n");
	 exit(0);
	}
	else
	 printf("Socket successfully created..\n");
	bzero(&servaddr,sizeof(servaddr));
	servaddr.sin_family=AF_INET;
	servaddr.sin_addr.s_addr=htonl(INADDR_ANY);
	servaddr.sin_port=htons(PORT);
	if((bind(sockfd,(SA*)&servaddr, sizeof(servaddr)))!=0)
	 {
	   printf("socket bind failed...\n");
	   exit(0);
	 }
	else
	    printf("Socket successfully binded..\n");
	if((listen(sockfd,5))!=0)
	  {
 	    printf("Listen failed...\n");
	    exit(0);
	   }
	else
	 printf("Server listening..\n");
	 len=sizeof(cli);
	 connfd=accept(sockfd,(SA *)&cli,&len);
	 if(connfd<0)
	  {
	    printf("server acccept failed...\n");
	    exit(0);
	  }
	 else
	  printf("server acccept the client...\n");
          func(connfd);
	  close(sockfd);
}// Main

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Read inputs from stdin

OneCompiler's C online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample C program which takes name as input and print your name with hello.

#include <stdio.h>
int main()
{
    char name[50];
    printf("Enter name:");
    scanf("%s", name);
    printf("Hello %s \n" , name );
    return 0;
    
}

About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition if-else is used.

if(conditional-expression) {
   // code
} else {
   // code
}

You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to if-else-if ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {  
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

How to declare a Function

return_type function_name(parameters);

How to call a Function

function_name (parameters)

How to define a Function

return_type function_name(parameters) {  
  //code
}