How would this code for the dining philosopher problem be altered to allow user

Question

How would this code for the dining philosopher problem be altered to allow user input for the amount of philosophers used? Thanks!

#include<stdio.h>

#include<semaphore.h>

#include<pthread.h>

#define N 5

#define THINKING 0

#define HUNGRY 1

#define EATING 2

#define LEFT (ph_num+4)%N

#define RIGHT (ph_num+1)%N

sem_t mutex;

sem_t S[N];

void * philospher(void *num);

void take_fork(int);

void put_fork(int);

void test(int);

int state[N];

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

int main()

{

    int i;

    pthread_t thread_id[N];

    sem_init(&mutex,0,1);

    for(i=0;i<N;i++)

        sem_init(&S[i],0,0);

    for(i=0;i<N;i++)

    {

        pthread_create(&thread_id[i],NULL,philospher,&phil_num[i]);

        printf("Philosopher %d is thinking ",i+1);

    }

    for(i=0;i<N;i++)

        pthread_join(thread_id[i],NULL);

}

void *philospher(void *num)

{

    while(1)

    {

        int *i = num;

        sleep(1);

        take_fork(*i);

        sleep(0);

        put_fork(*i);

    }

}

void take_fork(int ph_num)

{

    sem_wait(&mutex);

    state[ph_num] = HUNGRY;

    printf("Philosopher %d is Hungry ",ph_num+1);

    test(ph_num);

    sem_post(&mutex);

    sem_wait(&S[ph_num]);

    sleep(1);

}

void test(int ph_num)

{

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

    {

        state[ph_num] = EATING;

        sleep(2);

        printf("Philosopher %d takes fork %d and %d ",ph_num+1,LEFT+1,ph_num+1);

        printf("Philosopher %d is Eating ",ph_num+1);

        sem_post(&S[ph_num]);

    }

}

void put_fork(int ph_num)

{

    sem_wait(&mutex);

    state[ph_num] = THINKING;

    printf("Philosopher %d putting fork %d and %d down ",ph_num+1,LEFT+1,ph_num+1);

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

    test(LEFT);

    test(RIGHT);

    sem_post(&mutex);

}

Explanation / Answer

Hi, i got your query.

in your program you have predefined array i.e int phil_num[N]={0,1,2,3,4};

replace this line of your code with the following:

int phil_num[MAX_SIZE]; //Declares an array of MAX_SIZE
int p, W;

printf("Enter the total no of philosophers you want: ");

    scanf("%d", &W);

    printf("Enter %d philosophers : ", W);

    for(p=0; p<N; p++)

    {

        scanf("%d", &phil_num[p]);

    }

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