Help needed to solve problem with given code. language is C and should compile i

Question

Help needed to solve problem with given code. language is C and should compile in PuTTY.

#include<stdio.h>
#include<semaphore.h>
#include<pthread.h>

#define N 5 //the number of philosophers

sem_t S[N]; //semaphores for chopsticks

void * philospher(void *num);
void take_chopsticks(int);
void put_chopsticks(int);

int phil_num[N]={0,1,2,3,4}; //philosopher ID

int main()
{
int i;
pthread_t thread_id[N];


for(i=0;i<N;i++)
sem_init(&S[i],0,1);

for(i=0;i<N;i++)
pthread_create(&thread_id[i],NULL,philospher,&phil_num[i]);

for(i=0;i<N;i++)
pthread_join(thread_id[i],NULL);
}


void *philospher(void *num)
{
while(1)
{
int *i = num;
take_chopsticks(*i);
put_chopsticks(*i);
}
}

void take_chopsticks(int ph_num)
{
printf(
"Philosopher %d is Hungry ",ph_num);

sem_wait(&S[ph_num]); //take the left chopstick
printf("Philosopher %d takes chopstick%d ",ph_num, ph_num);

sleep(1);

sem_wait (&S[(ph_num+1)%N]); //take the right chopstick
printf("Philosopher %d takes chopstick%d ",ph_num,(ph_num+1)%N);

printf("Philosopher %d is eating ",ph_num);
sleep(1);
  
}


void put_chopsticks(int ph_num)
{

sem_post (&S[ph_num]); //put the left chopstick
printf("Philosopher %d putting chopstick%d ",ph_num, ph_num);

sleep(1);

sem_post (&S[(ph_num+1)%N]); //put the right chopstick
printf("Philosopher %d putting chopstick%d ",ph_num,(ph_num+1)%N);

printf("Philosopher %d is thinking ",ph_num);
sleep(1);
}

3. Use an asymmetric solution an odd-numbered philosopher picks up first the left chopstick and then the right chopstick Even-numbered philosopher picks up first the right chopstick and then the left chopstick

Explanation / Answer

Ans:

# include<stdio.h> // STDIO.H

# include<pthread.h> // pthread

# include<stdlib.h> // stdlib

# include<unistd.h> // unistd

# include<ctype.h> // ctype

# include<sys/types.h> // sys/types

# include<sys/wait.h> // wait

# include<semaphore.h> // semaphore.h

// defines N 5

#define N 5   

// left

#define LEFT (i+4)%N

// right

#define RIGHT (i+1)%N

// thinking

#define THINKING 0

// hungry

#define HUNGRY 1

// eating_2

#define EATING 2

// spoon

sem_t spoon;

// semaphore phil

sem_t phil[N];

// int state[N]

int state[N];

// 0,1,2,3,4

int phil_num[N]={0,1,2,3,4};

// fd[N][2]

int fd[N][2]; // file descriptors for the pipes

pid_t pid, pids[N]; // proces_id's

// int i

int i;

//int num

int num;

// void phil

void philosopher(int i);

// test

void test(int i);

void take_spoon(int i);

// spoon

void put_spoon(int i);

// buffer char

char buffer[100];

// main

int main(void)

{

// for loop

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

{

// pipe

pipe(fd[i]);

// pids

pids[i] = fork();

// printf

printf("i=%d ",i);

// prints pids

printf("pids[i]=%d ",pids[i]);

// pid[i] == 0

if(pids[i]==0)

{

//for the child

//dup2

dup2(fd[i][1],1);

// close

close(fd[i][0]);

// close [i] [1]   

close(fd[i][1]);

// phil(i)

philosopher(i);

// exit

_exit(0);

}

// else

else if(pids[i]>0)

{

//for the parent

// dup2 fd,0

dup2(fd[i][0],0);

// close

close(fd[i][0]);

// close [i][1]

close(fd[i][1]);

}

}

// wait for the child proceses to become end

// for loop , wait

for(i=0;i<N;++i) waitpid(pids[i],NULL,0);

// return

return 0;

}

// void pholospher()

void philosopher(int i)

{

// while 1

while(1)

{

// sleep(1)

sleep(1);

// spoon(1)

take_spoon(i);

// sleep2

sleep(2);

// put spoon

put_spoon(i);

// sleep 1

sleep(1);

}

}

// void take spoon fun

void take_spoon(int i)

{

// wait

sem_wait(&spoon);

// hungry

state[i] = HUNGRY;

// prints hungry

printf("philosopher %d hungry ",i+1);

// tets

test(i);

// // post

sem_post(&spoon);

// wait. phil[1]

sem_wait(&phil[i]);

}

// put-sppoon()

void put_spoon(int i)

{

// semaphore_wait

sem_wait(&spoon);

// thinking cond

state[i] = THINKING;

// prints message

printf("philosopher %d put_down the spoon %d & %d hin ",i+1,LEFT+1,i+1);

// prints message

printf("philosophr %d think's ",i+1);

// test_)left

test(LEFT);

// test_right

test(RIGHT);

// sem post()

sem_post(&spoon);

}

// void_test()

void test(int i)

{

// if hungry and not eating

if( state[i] == HUNGRY && state[LEFT] != EATING && state[RIGHT] != EATING)

{

// eating

state[i] = EATING;

// prints the condition

printf("philosopher %d take's the spoon %d & %d ",i+1,LEFT+1,i+1);

// prints eats

printf("philosophr %d eat's ",i+1);

// sem post phil[i]

sem_post(&phil[i]);

}

}

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