C 合并排序中的逻辑错误

leftIndex您已经问了这个问题。谢谢！这就解决了问题。
#include<stdio.h>
#include<stdlib.h>
typedef struct points{
        float axis[2];
        int id;
}Points;

typedef enum{
        SortById,
        SortByXAxis
}SortType;

Points* fill_Array(char* filename, int* length);
void Print_set(Points* set, int number_of_points);
void mergesort(Points* set, int low, int high, int number_of_points,SortType sort);
void merge(Points* set, int low, int middle, int high, int number_of_points,SortType sort);

int main(int argc, char* argv[])
{
    int length;
    Points *array;
    array=fill_Array(argv[1],&length);
    Print_set(array,length);
    printf("\n\n");
    mergesort(array,0,length,length,SortById);
    Print_set(array,length);
    return 0;
}
Points* fill_Array(char* filename,int* length)
{
    int i;
    Points* array;
    FILE* file=fopen(filename,"r");

    if(file == NULL)
    {
        return NULL;
    }

    fscanf(file,"%d",length);
    array=malloc(sizeof(Points)* *length);

    for(i = 0; i < *length; i++)
    {
        fscanf(file,"%d %f %f", &(array+i)->id,&(array+i)->axis[0],&(array+i)->axis[1]);
    }
    fclose(file);

    return array;
}

void Print_set(Points *set, int number_of_points)
{
    int i;

    for(i = 0; i < number_of_points; i++)
    {
        printf("%d %f %f\n",(set+i)->id,(set+i)->axis[0],(set+i)->axis[1]);
    }
}

void mergesort(Points* set,int low,int high,int number_of_points, SortType sort)
{
    int mid1;

    if((high-low)>1)
    {
        mid1 = (low+high)/2;

        mergesort(set, low, mid1, number_of_points, sort);
        mergesort(set, mid1, high, number_of_points, sort);
        merge(set, low, mid1, high, number_of_points, sort);

    }

}
void merge(Points* set, int low, int middle, int high, int number_of_points, SortType sort)
{
        int leftIndex=low;
        int rightIndex=middle;
        int combinedIndex = low;
        Points tempArray[number_of_points];
        int i;

        while(leftIndex <= middle && rightIndex < high)
        {
            if(set[leftIndex].id <= set[rightIndex].id)
            {
                tempArray[combinedIndex++] = set[leftIndex++];
            }
            else
                tempArray[combinedIndex++] = set[rightIndex++];
        }

        if(leftIndex == middle+1)
        {
            while(rightIndex < high)
            {
                tempArray[combinedIndex++] = set[rightIndex++];
            }
        }
        else
        {
            while(leftIndex < middle)
            {
                tempArray[combinedIndex++] = set[leftIndex++];
            }
        }

        for( i = low; i < high; i++)
        {
            set[i] = tempArray[i];
        }
}

1 13.000000 7.000000
13 14.000000 6.000000
95 7.000000 13.000000
39 0.000000 20.000000
78 10.000000 10.000000
68 3.000000 17.000000
32 6.000000 14.000000
10 19.000000 1.000000
0 18.000000 2.000000
45 17.000000 3.000000
92 4.000000 16.000000
29 5.000000 15.000000
85 8.000000 12.000000
79 15.000000 5.000000
12 16.000000 4.000000
32 1.000000 19.000000
77 9.000000 11.000000
52 12.000000 8.000000
80 11.000000 9.000000
31 2.000000 18.000000


0 18.000000 2.000000
1 13.000000 7.000000
10 19.000000 1.000000
0 18.000000 2.000000
12 16.000000 4.000000
13 14.000000 6.000000
29 5.000000 15.000000
31 2.000000 18.000000
32 6.000000 14.000000
32 1.000000 19.000000
39 0.000000 20.000000
39 0.000000 20.000000
52 12.000000 8.000000
31 2.000000 18.000000
68 3.000000 17.000000
77 9.000000 11.000000
78 10.000000 10.000000
12 16.000000 4.000000
79 15.000000 5.000000
85 8.000000 12.000000