Question

Valgrind在某些方面抱怨我的代码，我真的不知道为什么..我基本上已经完成了合并排序（降序）的代码并对其进行了调整，因为我希望以后不要有排序列表，而只是它的元素现在的顺序，所以如果我有：

5 8 1 2
[0] [1] [2] [3]，排序后是：

8 5 2 1

[1] [0] [3] [2]＆lt; ==这就是我想要的

所以我的代码分为三部分：

int main(int argc, char** argv) {

int *llist, *array_ordered;
int end,fst, i ; //will be set somehow
array_ordered = malloc(sizeof(int)*(end-fst));
llist = malloc(sizeof(int)*(end-fst)); //filled with some numbers
for(i =0; i < (end-fst); i++) array_ordered[i] = i;

 sort_list(end-fst, llist, array_ordered);

}

void sort_list(int total, int *llist, int *array_ordered) {

  int i, j, temp, *temp_array; 
  temp_array = malloc(sizeof(int)*total);

  for (i = 0; i < total; i++) {
  temp_array[i] = llist[i]; // copying the values, because I need my original list to keep
  }
  merge_sort(temp_array, total, array_ordered);
 free(temp_array);

}

void merge_sort(int *A, int total_el, int *array_ordered) {
  int i;
  int *list_one, *list_two;
  int *order_one, *order_two;
  int num1, num2;

  if (total_el < 2) return;   /* the array is sorted when n=1.*/

  /* divide A into two parths the list, and the positions (array_ordered)*/
  num1 = total_el / 2;   /* the number of elements in A1 */
  num2 = total_el - num1;  /* the number of elements in A2 */
  list_one = malloc(sizeof(int)*num1);
  list_two = malloc(sizeof(int)*num2);
  order_one = malloc(sizeof(int)*num1);
  order_two = malloc(sizeof(int)*num2);

  /* move the first n/2 elements to A1 */
  for (i =0; i < num1; i++) {
    list_one[i] = A[i];
    order_one[i] = array_ordered[i];   <=== invalid read of size 4
  }
 for (i = 0; i < num2; i++) {
    list_two[i] = A[i+num1];
   order_two[i] = array_ordered[i+num1];  <=== invalid read of size 4
 }

 merge_sort(list_one, num1, order_one);
 merge_sort(list_two, num2, order_two);

 merge(list_one, num1, list_two, num2, A, array_ordered, order_one, order_two);
 free(list_one);
 free(list_two);
 free(order_one);
 free(order_two);

}

 void merge (int *A, int a, int *B, int b, int *C, int *array_ordered, int *order_one, int  *order_two) {
  int i,j,k;
  i = j = k = 0; 

  while (i < a && j < b) {
    if (A[i] >= B[j]) {
    /* copy A[i] to C[k] and move the pointer i and k forward */
      C[k] = A[i];
      array_ordered[k] = order_one[i];    <=== Invalid write of size 4!
      i++;
      k++;
    }
    else {
      /* copy B[j] to C[k] and move the pointer j and k forward */
      C[k] = B[j];
      array_ordered[k] = order_two[j];
      j++;
      k++;
    }
  }
  /* move the remaining elements in A into C */
  while (i < a) {
    C[k]= A[i];
    array_ordered[k] = order_one[i];
    i++;
    k++;
  }
 /* move the remaining elements in B into C */
  while (j < b)  {
    C[k]= B[j];
    array_ordered[k] = order_two[j];
    j++;
    k++;
  }
}

我不知道，因为所有列表都有相同的总数，为什么我只会在非法位置列表中的某一点写：S

==1373== Invalid read of size 4
==1373==    at 0x10001F1D5: merge_sort (main.c:5586)
==1373==    by 0x10001D2E0: sort_list (main.c:5512)
==1373==    by 0x10000A164: my_function (main.c:1014)
==1373==    by 0x1000032E5: main (main.c:450)
==1373==  Address 0x244fd9a70 is 0 bytes inside a block of size 1,512 free'd
==1373==    at 0x4D9D: free (vg_replace_malloc.c:479)
==1373==    by 0x10000A1A4: my_function (main.c:1020)
==1373==    by 0x1000032E5: main (main.c:450)

and 
==1373== Invalid write of size 4
==1373==    at 0x10001F3BC: merge (main.c:5529)
==1373==    by 0x10001F2C0: merge_sort (main.c:5602)
==1373==    by 0x10001D2E0: sort_list (main.c:5512)
==1373==    by 0x10000A164: my_function (main.c:1014)
==1373==    by 0x1000032E5: main (main.c:450)
==1373==  Address 0x244fd9a70 is 0 bytes inside a block of size 1,512 free'd
==1373==    at 0x4D9D: free (vg_replace_malloc.c:479)
==1373==    by 0x10000A1A4: my_function (main.c:1020)
==1373==    by 0x1000032E5: main (main.c:450)

合并排序C中的写入和读取无效

0 个答案: