在java中为了避免 low+high溢出，可以用无符号右移：正数高位补0，负数高位补1
int mid = (low + high) >>> 1;
如果是在c++中，那么需要先转换为unsigned的再移位
int a=100;
int b;
b=((unsigned int)a)>>1;
或者 int mid = low + ((high - low) / 2);
public static int binarySearch(int[] a, int target) {
int low = 0;
int high = a.length - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
int midVal = a[mid];
if (midVal < target)
low = mid + 1;
else if (midVal > target)
high = mid - 1;
else
return mid;
}
return -1;
}
原文：http://www.cnblogs.com/juandx/p/4083391.html