// C program for the Server Side
// inet_addr
#include <arpa/inet.h>
// For threading, link with lpthread
#include <pthread.h>
#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>
// Semaphore variables
sem_t x, y;
pthread_t tid;
pthread_t writerthreads[100];
pthread_t readerthreads[100];
int readercount = 0;
// Reader Function
void* reader(void* param)
{
// Lock the semaphore
sem_wait(&x);
readercount++;
if (readercount == 1)
sem_wait(&y);
// Unlock the semaphore
sem_post(&x);
printf("\n%d reader is inside",
readercount);
sleep(5);
// Lock the semaphore
sem_wait(&x);
readercount--;
if (readercount == 0) {
sem_post(&y);
}
// Lock the semaphore
sem_post(&x);
printf("\n%d Reader is leaving",
readercount + 1);
pthread_exit(NULL);
}
// Writer Function
void* writer(void* param)
{
printf("\nWriter is trying to enter");
// Lock the semaphore
sem_wait(&y);
printf("\nWriter has entered");
// Unlock the semaphore
sem_post(&y);
printf("\nWriter is leaving");
pthread_exit(NULL);
}
// Driver Code
int main()
{
// Initialize variables
int serverSocket, newSocket;
struct sockaddr_in serverAddr;
struct sockaddr_storage serverStorage;
socklen_t addr_size;
sem_init(&x, 0, 1);
sem_init(&y, 0, 1);
serverSocket = socket(AF_INET, SOCK_STREAM, 0);
serverAddr.sin_addr.s_addr = INADDR_ANY;
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = htons(8989);
// Bind the socket to the
// address and port number.
bind(serverSocket,
(struct sockaddr*)&serverAddr,
sizeof(serverAddr));
// Listen on the socket,
// with 40 max connection
// requests queued
if (listen(serverSocket, 50) == 0)
printf("Listening\n");
else
printf("Error\n");
// Array for thread
pthread_t tid[60];
int i = 0;
while (1) {
addr_size = sizeof(serverStorage);
// Extract the first
// connection in the queue
newSocket = accept(serverSocket,
(struct sockaddr*)&serverStorage,
&addr_size);
int choice = 0;
recv(newSocket,
&choice, sizeof(choice), 0);
if (choice == 1) {
// Creater readers thread
if (pthread_create(&readerthreads[i++], NULL,
reader, &newSocket)
!= 0)
// Error in creating thread
printf("Failed to create thread\n");
}
else if (choice == 2) {
// Create writers thread
if (pthread_create(&writerthreads[i++], NULL,
writer, &newSocket)
!= 0)
// Error in creating thread
printf("Failed to create thread\n");
}
if (i >= 50) {
// Update i
i = 0;
while (i < 50) {
// Suspend execution of
// the calling thread
// until the target
// thread terminates
pthread_join(writerthreads[i++],
NULL);
pthread_join(readerthreads[i++],
NULL);
}
// Update i
i = 0;
}
}
return 0;
}
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#include <stdio.h>
int main()
{
char name[50];
printf("Enter name:");
scanf("%s", name);
printf("Hello %s \n" , name );
return 0;
}
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.
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.
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;
}
For loop is used to iterate a set of statements based on a condition.
for(Initialization; Condition; Increment/decrement){
// code
}
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
}
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);
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.
data-type array-name[size];
data-type array-name[size][size];
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
Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,
User defined functions are the ones which are written by the programmer based on the requirement.
return_type function_name(parameters);
function_name (parameters)
return_type function_name(parameters) {
//code
}