Answer:
The program to this question can be given as:
program:
/*define header files.*/
#include <stdio.h> /* For printf, scanf, puts */
#include <pthread.h> /* For various thread functions */
#include <math.h> /* For sqrt */
#include <stdlib.h> /* For calloc */
#include <assert.h>
typedef struct /* define structure.*/
{
/* Store the thread's current status. */
pthread_cond_t start_working;
/* This mutex protects the condition variable. */
pthread_mutex_t cond_mutex;
/* To what number is the thread searching? */
long max_search;
} thread_parameters_t;
typedef struct {
long f[2];
} factor_t;
/* This function prints prime factorizations. */
void factorization(long n, factor_t *sieve) {
int i;
if (sieve[n].f[0]) {
for (i = 0; i < 2; ++i)
if (sieve[n].f[i])
factorization(sieve[n].f[i], sieve);
} else
printf(" %ld ", n);
}
/* This function runs the prime computer */
void *primes_computer_runner(void *param) {
factor_t *sieve;
long i, prime, limit;
thread_parameters_t *thread_parameters = (thread_parameters_t*)param;
pthread_mutex_lock(&thread_parameters->cond_mutex);
pthread_cond_wait(&thread_parameters->start_working,
&thread_parameters->cond_mutex);
/* Now our thread sleeps until the condition is true. *
* When it reaches the next line, it has been signaled from *
* the main thread. */
printf("Thread woken up to find primes less than %ld.\\",
thread_parameters->max_search);
/* We use the Sieve of Eratosthenes here. */
sieve = (factor_t*)calloc(thread_parameters->max_search, sizeof(factor_t));
assert(sieve != NULL);
/* Because calloc helpfully initalizes our memory to 0, we will *
* use 0 to represent "is prime" in accordance with the algorithm. */
limit = (long)sqrt(thread_parameters->max_search) + 1;
/* the 'prime' here is really a prime-presumptive, of course. */
for (prime = 2; prime <= limit; ++prime)
for (i=2; i*prime < thread_parameters->max_search; ++i) {
sieve[i*prime].f[0] = i;
sieve[i*prime].f[1]= prime;
/* It is nonprime because it has factors *
* i and prime... */
}
/* Display the results */
for(i=2; i < thread_parameters->max_search; ++i)
if (!sieve[i].f[0])
printf("* %ld is prime.\\",i);
#ifdef SHOW_NONPRIME
else {
printf(" %ld is nonprime, factorization: (",i);
factorization(i, sieve);
puts(")");
}
#endif
free(sieve);
return NULL;
}
int main (int argc, char *argv[]) {
/* We pass a pointer to this struct to the computational thread. */
thread_parameters_t thread_parameters;
/* Set up the initial conditions of our thread */
pthread_cond_init(&thread_parameters.start_working, NULL);
pthread_mutex_init(&thread_parameters.cond_mutex, NULL);
/* This thread will do the computing of prime numbers. */
pthread_t computational_thread;
/* Create and start our new thread. */
pthread_create(&computational_thread, NULL, primes_computer_runner,
(void*)&thread_parameters);
puts("Prime Number Calculator Program with Threads\\"
"Enter an integer and the program will print all primes less than\\"
#ifdef SHOW_NONPRIME
"This program has been compiled to show prime factorizations of \\"
"the nonprimes it finds, with -DSHOW_NONPRIME in the Makefile.\\"
#endif
);
/* Get the integer from the user */
if (!scanf("%ld", &thread_parameters.max_search)) return 0;
/* Wake up the thread to do the computation. */
pthread_cond_broadcast(&thread_parameters.start_working);
/* Wait for it to finish (makes this rather pointless, but I forgot
* about this assignment until the eleventh hour.) */
pthread_join(computational_thread,NULL);
return 0;
}
Output:
Prime Number Calculator Program with Threads
Enter an integer and the program will print all primes less than:
6
Thread woken up to find primes less than 6.
* 2 is prime.
* 3 is prime.
* 5 is prime.
Explanation:
In the above Pthreads program, It prints all the prime numbers. the working of this program as follows. firstly we define the structure that uses the typedef keyword this keyword is used for provides user-define data-type. Then we use the two functions that are given below.
1). factorization
2.) *primes_computer_runner
The both function does not return a value because its datatype is void. In the first function, It is used to collect all the numbers and pass into the second function. This function is pointer type and it is used for checking the value that is inserted by the user and print the prime number less than the inserted value. In the last, we define the main function that takes the value from the user by command line and we pass the value as a parameter in the above function.