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; }