Java入门：一些初学者需要掌握的基础算法程序——二分查找

import java.util.Scanner;
class BinarySearchExample
{
public static void main(String args[])
{
int counter, num, item, array[], first, last, middle;
//To capture user input
Scanner input = new Scanner(System.in);
System.out.println("Enter number of elements:");
num = input.nextInt();

//Creating array to store the all the numbers
array = new int[num];

System.out.println("Enter " + num + " integers");
//Loop to store each numbers in array
for (counter = 0; counter < num; counter++)
array[counter] = input.nextInt();

System.out.println("Enter the search value:");
item = input.nextInt();
first = 0;
last = num - 1;
middle = (first + last)/2;

while( first <= last )
{
if ( array[middle] < item )
first = middle + 1;
else if ( array[middle] == item )
{
System.out.println(item + " found at location " + (middle + 1) + ".");
break;
}
else
{
last = middle - 1;
}
middle = (first + last)/2;
}
if ( first > last )
System.out.println(item + " is not found.\n");
}
}

Enter number of elements:
7
Enter 7 integers
4
5
66
77
8
99
0
Enter the search value:
77
77 found at location 4.

Enter number of elements:
5
Enter 5 integers
12
3
77
890
23
Enter the search value:
99
99 is not found.