#include<stdio.h>/* import required library for code to run*/ 
#include<stdlib.h>
#include<pthread.h>
#include<semaphore.h>
#include<unistd.h>
sem_t chopstick[5]; /* global variable number of chopstick ,Making an Array of length 5*/ 
void * philos(void *); /* golbal vaiable for phiolospher*/ 
void eat(int); /* function decration for eat function*/ 

 void eat(int ph)
 {
         printf("Philosopher %d begins to eat\n",ph);/* the function decalred for eating function*/ 
 }

void * philos(void * n)
 {/* the function for philospher*/ 
         int ph=*(int *)n;
         printf("Philosopher %d wants to eat\n",ph); 
         printf("Philosopher %d tries to pick left chopstick\n",ph);
         sem_wait(&chopstick[ph]);/* This function  sem_wait will locks sen semaphore referen by the sem by perform a semaphore locking operation on the semaphore.*/ 
         printf("Philosopher %d picks the left chopstick\n",ph);
         printf("Philosopher %d tries to pick the right chopstick\n",ph);
         sem_wait(&chopstick[(ph+1)%5]);/*This function locks the semaphore referenced by sem by performing a semaphore lock operation on that semaphore.*/ 
         printf("Philosopher %d picks the right chopstick\n",ph);
         eat(ph); /* Output the number of Philosopher named as 'ph' that has begin to eat.*/ 
         sleep(2);/* The Thread that is Current thread will go into the sleep for 2 seconds time period.*/ 
         printf("Philosopher %d has finished eating\n",ph);
         sem_post(&chopstick[(ph+1)%5]);/* The sem_post function to Unlock the semaphore*/ 
         printf("Philosopher %d leaves the right chopstick\n",ph);
         sem_post(&chopstick[ph]);/*  The sem_post function to Unlock the semaphore Unlock the semaphore*/ 
         printf("Philosopher %d leaves the left chopstick\n",ph);
 }

 int main()
 {
         int i,n[5]; /* variable intialised for loop and other things.*/ 
         pthread_t T[5]; /* The number of thread*/ 
         for(i=0;i<5;i++)/* loop that runs for number of process or persons that will eat the from chopsticks*/ 
         sem_init(&chopstick[i],0,1); /* This function  sem_wait will locks sen semaphore referen by the sem by perform a semaphore locking operation on the semaphore.*/ 
         for(i=0;i<5;i++){/*this loop will create the number of threads defined in loop*/ 
                 n[i]=i;
                 pthread_create(&T[i],NULL,philos,(void *)&n[i]);
                 }
         for(i=0;i<5;i++)
                 pthread_join(T[i],NULL);/*this loop will waits for the the termination.*/ 
 }

C Language online compiler

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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
}