C语言 带比较器的归并排序

#include <stdio.h>
#include <stdlib.h>

typedef int DataType;

//比较器
int mycmp(const void * a, const void *b); 

//int (*compar)(const void *, const void *) 函数指针
void Sort(DataType * arr, int from, int to, int (*compar)(const void *, const void *));

void merge(DataType *arr, int from, int mid, int to, int (*compar)(const void *, const void *));

void printArray(DataType * arr, int n);

int main()
{
    DataType arr[10] = {2,3,10,12,6,1,18,14,65,12};
    printf("Befor sort:\n");
    printArray(arr,10);
    Sort(arr, 0, 9, mycmp);
    printf("After sort:\n");
    printArray(arr,10);
    return 0;
}

void Sort(DataType * arr, int from, int to, int (*compar)(const void *, const void *))
{
    if(from == to)
        return;
    DataType mid = (from + to)/2;
    Sort(arr, from, mid, *compar);
    Sort(arr, mid+1, to, *compar);
    merge(arr, from, mid, to, *compar);

}

void merge(DataType * arr, int from, int mid, int to, int (*compar)(const void *, const void*))
{
    int i = 0;
    DataType * first1 = arr + from;
    DataType * end1 = arr + mid + 1;
    DataType * first2 = arr + mid + 1;
    DataType * end2 = arr + to + 1;
    DataType * temp = (DataType *)malloc((to - from + 1)*sizeof(DataType));
    DataType * p = temp;
    while((first1 != end1) && (first2 != end2))
        *p++ = ((*compar)(first1, first2) ? *first1++ : *first2++); 
    if(first1 == end1)
    {
        while(first2 != end2)
            *p++ = *first2++; 
    }
    else
    {
        while(first1 != end1)
            *p++ = *first1++;
    }
    p = temp;
    for(int i = from; i <= to; i++)
        arr[i] = *p++;
    free(temp);
}

int mycmp(const void * a, const void *b)
{
    const DataType * pa = (const DataType *)a;
    const DataType * pb = (const DataType *)b;
    if(*pa >= *pb)
        return 1;
    else 
        return 0;
}

void printArray(DataType * arr, int n)
{
    for(int i = 0; i < n; i++)
        printf("%d ", arr[i]);
    printf("\n");
}