二分查找的一個重要前提：表中的元素必須有序，且僅限于順序存儲結(jié)構(gòu)。

include <iostream>

using namespace std;

int BinarySearch(int *a, int n, int key);

//注意：表中的元素必須有序，且僅限于順序存儲結(jié)構(gòu)
int BinarySearch(int *a, int n, int key)
{
int low = 0;
int high = n - 1;
while (low <= high)
{
int mid = (low + high) / 2;
if (a[mid] == key)
{
return mid;
}
if (key < a[mid]) //往左區(qū)間找
{
high = mid - 1;
}
else //往右區(qū)間找
{
low = mid + 1;
}
}

return -1;

}

int main()
{
int a[11] = {5, 16, 20, 27, 30, 36, 44, 55, 60, 67, 71};
int n = 11;

cout << "search 27 = " << BinarySearch(a, n, 27) << endl;
cout << "search 65 = " << BinarySearch(a, n, 65) << endl;
cout << system("pause");
return 0;

}

參考資料：《數(shù)據(jù)結(jié)構(gòu)（C語言版）》p166-p169