Question

我在pthread中使用C创建了一个矩阵乘法程序。但是当我编译我的程序时，我得到了一些警告和注意。我尽力解决这个问题。我无法做到这一点。我在下面提到了我的警告和注意事项。

warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] int s = (int)threadid;

warning: passing argument 1 of ‘multiply’ makes pointer from integer without a cast [-Wint-conversion] multiply(i);

note: expected ‘void *’ but argument is of type ‘int’ void* multiply(void *threadid)

代码：

#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#define SIZE 1024

int num_thrd;

int A[SIZE][SIZE], B[SIZE][SIZE], C[SIZE][SIZE];

int randnumgen(){
  return rand()%10 +1 ;
}

void init_matrix(int m[SIZE][SIZE])
{
 int i, j, val = 0;
 for (i = 0; i < SIZE; i++)
 {
   for (j = 0; j < SIZE; j++)
   {
     m[i][j] = randnumgen();
   }
  }
}

void print_matrix(int m[SIZE][SIZE])
{
  int i, j;
  for (i = 0; i < SIZE; i++) {
  printf("\n\t| ");
  for (j = 0; j < SIZE; j++)
     printf("%2d ", m[i][j]);
     printf("|");
   }
}

// thread function
void* multiply(void *threadid)
{  
  int s = (int)threadid;
  int from = (s * SIZE)/num_thrd;
  int to = ((s+1) * SIZE)/num_thrd;
  int i,j,k;

  clock_t begin = clock();

  for (i = from; i < to; i++)
  {  
    for (j = 0; j < SIZE; j++)
    {
      C[i][j] = 0;
      for ( k = 0; k < SIZE; k++)
      C[i][j] += A[i][k]*B[k][j];
    }
  }


  return 0;
}

int main(int argc, char* argv[])
{
  pthread_t* thread;
  int i;
  double runtime=0;

  num_thrd = atoi(argv[1]);
  init_matrix(A);
  init_matrix(B);
  thread = (pthread_t*) malloc(num_thrd*sizeof(pthread_t));


  clock_t begin = clock();

   for (i = 0; i < num_thrd; i++){

    multiply(i);
   }

  clock_t end = clock();
  runtime = (double)(end - begin) / CLOCKS_PER_SEC;
  printf("%f\n",runtime);

  free(thread);

  return 0;

}

-Cp线程程序中的-Wpointer-to-int-cast和-Wint-conversion警告

0 个答案: