C语言二分查找法

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

int halfSearch(int data[], unsigned int len, int key)
{
int low = 0;
int high = len;
while(low <= high)
{
int midder = (low+high)/2;
if(data[midder] == key)
{
return midder;
}
else if(data[midder] > key)
{
high = midder-1;
}
else
{
low = midder+1;
}
}
return -1;
}

int main()
{
int data[] = {0,1,2,3,4,5,6,7,8,9};
int pos;
printf("please input number between 0 and 9 : ");
scanf("%d", &pos);
printf("find index %d\n", pos, halfSearch(data, sizeof(data)/sizeof(int), pos));
system("pause");
return 0;
}