package create; 
public class Demo1_Array {
	public static void main(String[] args){
		int[] arr = {11,22,33,44,55,66,77};
		System.out.println(getIndex(arr,22));
		System.out.println(getIndex(arr,77));
		System.out.println(getIndex(arr,88));		
	}
	
	public static int getIndex(int[] arr,int value){
		int min=0;
        int max=arr.length-1;
        int mid;	
		while(min<=max){
			mid=(max+min)/2;
			if(arr[mid]==value){
				return mid;
			}else if(arr[mid]<value){
				min=mid+1;
			}else{
				max=mid-1;
			}
		}
		return -1;
	}
}

//以下程式碼有誤			
		/*while(arr[mid]!=value){//中間值不等於所求值，開始迴圈查詢
			if(arr[mid]<value){
				min=mid+1;
			}else if(arr[mid]>value){
					min=mid-1;
				}
			mid=(min+max)/2;
			
			if(min>max){
				return -1;
			}
		}//while結束
		return mid；
		*/