c - 我的代码只计算一系列中的前两个素数并停止我无法弄清楚为什么它在计算其余素数之前停止

Question

这是我用 4 个线程实现的素数计算器的 C 实现，它仅在 2 个素数后停止。我真的很感激任何让它工作的帮助和任何让它更快的帮助。预先感谢您

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <math.h>
#include <assert.h>
#include <pthread.h>
#include <limits.h>

unsigned long *ary;
unsigned long max;


struct arg_struct{
  unigned long start;
  unsigned long end;
};


void * thread_do(void * input){
  unsigned long i, j;
  struct arg_struct * param = input;
  for (i = 3; i <= sqrt(max) + 1; i += 2) {
    for (j = param->start; j < param->end; j++) {
      if (ary[j] && ary[j] % i == 0 && ary[j] != i) {
    ary[j] = 0;
      }
    }
  }

  return NULL;
}

unsigned long *sieve_of_eratosthenes(unsigned long begin, unsigned long end){
  unsigned long i, j = 0, interval, arylen;
  pthread_t *threads = malloc(sizeof(pthread_t *) * 4);
  void *thread_return_value;
  max = end;

  struct arg_struct *thread1 = malloc(sizeof(struct arg_struct));;
  struct arg_struct *thread2 = malloc(sizeof(struct arg_struct));;
  struct arg_struct *thread3 = malloc(sizeof(struct arg_struct));;
  struct arg_struct *thread4 = malloc(sizeof(struct arg_struct));;

  /* skip initial even or initial 1 */
  while (begin == 1 || begin % 2 == 0)
    begin += 1;

  /* possible that begin==end==5; result array should be 5, 0 */
  arylen = end - begin + 2;

  ary = calloc(arylen + 1, sizeof(unsigned long));
  if (!ary)
    exit(1);

  /* setup the odds-only array. */
  for (i = begin; i <= end; i += 2) {
    ary[(i - begin) / 2] = i;
  }

  interval = end - begin;
  thread1->start = begin;
  thread1->end = begin + interval/4;

  thread2->start = begin + interval/4 + 1;
  thread2->end = begin + interval/2;

  thread3->start = begin + interval/2 + 1;
  thread3->end = begin + (3 * interval)/4;

  thread4->start = begin + (3 * interval)/4 + 1;
  thread4->end = end;

  /* clear non-primes with threads*/
  pthread_create(&threads[0], NULL, thread_do, thread1);
  pthread_create(&threads[1], NULL, thread_do, thread2);
  pthread_create(&threads[2], NULL, thread_do, thread3);
  pthread_create(&threads[3], NULL, thread_do, thread4);


  j = 0;
  for (i = 0; i < arylen && j < arylen; i++) {
    for (; j < arylen && ary[j] == 0; j++);
      if (j < arylen) {
        assert(ary[j] != 0);
        assert(i <= j);
        ary[i] = ary[j];
      } else {
        break;
      }
      j++;
    }

  for(i = 0; i < 4 ; i++){
    pthread_join(threads[i], &thread_return_value);
  }


  ary[i] = 0;
  ary = realloc(ary, (i + 1) * sizeof(unsigned long));

  return ary;
}

Answer 1

GCC(Gnu 编译器集合)返回以下错误。

h.c:14:3: error: expected specifier-qualifier-list before ‘unigned’
   unigned long start;
   ^
h.c: In function ‘thread_do’:
h.c:23:19: error: ‘struct arg_struct’ has no member named ‘start’
     for (j = param->start; j < param->end; j++) {
                   ^
h.c:23:37: error: ‘struct arg_struct’ has no member named ‘end’
     for (j = param->start; j < param->end; j++) {
                                     ^
h.c: In function ‘sieve_of_eratosthenes’:
h.c:61:10: error: ‘struct arg_struct’ has no member named ‘start’
   thread1->start = begin;
          ^
h.c:62:10: error: ‘struct arg_struct’ has no member named ‘end’
   thread1->end = begin + interval/4;
          ^
h.c:64:10: error: ‘struct arg_struct’ has no member named ‘start’
   thread2->start = begin + interval/4 + 1;
          ^
h.c:65:10: error: ‘struct arg_struct’ has no member named ‘end’
   thread2->end = begin + interval/2;
          ^
h.c:67:10: error: ‘struct arg_struct’ has no member named ‘start’
   thread3->start = begin + interval/2 + 1;
          ^
h.c:68:10: error: ‘struct arg_struct’ has no member named ‘end’
   thread3->end = begin + (3 * interval)/4;
          ^
h.c:70:10: error: ‘struct arg_struct’ has no member named ‘start’
   thread4->start = begin + (3 * interval)/4 + 1;
          ^
h.c:71:10: error: ‘struct arg_struct’ has no member named ‘end’
   thread4->end = end;
          ^

主要错误之一是内存分配问题，是您使用的是 unsigned 而不是 unsigned:)。