string类的写时拷贝

//leftindex 是开始下表 0 rightindex 是值得最大长度-1 val 要查找的值，arr[] 存放数值的数组

public void find(int leftindex,int rightindex,int val,int arr[])

{

//首先找到中间的数

int midindex =(leftindex+rightindex)/2;

int midval =arr[midindex];

 

             if(rightindex>=leftindex){

           //System.out.println("23232");

 

               //如果找到的数比midval 大

                            if(midval>val){

                                     //在arr左边的数中找

                                       find(leftindex,midindex-1,val,arr);

 

                                   }else if(midval<val){

                                        //在arr右边中找

                                       find(midindex+1,rightindex,val,arr);

                               }else if(midval==val){

                                           System.out.println("找到下表"+ midindex);

                                                   }

 

                       }

}