二分法查找一维数组

beyes

代码：

#include <stdio.h>
#include <stdlib.h>

int find_number (int *p, int num, int val);

int main()
{
        int a [15] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
        int val;
        int *p = a;
        int num = 15;
        int ret;

        printf ("Input a number which want to find: ");

        scanf ("%d", &val);

        ret = find_number (p, num, val);

        if (ret == -1) {
                printf ("Can not find out the number\n");
                exit (1);
        }
        printf ("find out the number at array position: %d \n", ret);
        return (0);
}

int find_number (int *p, int num, int val)
{
        int high = num;
        int low = 0;
        int mid;

        while (low <= high) {
                mid = (low + high) / 2;

                if (val == *(p + mid))
                        return (mid);

                if (val > *(p + mid))
                        low = mid + 1;

                if (val < *(p + mid))
                        high = mid - 1;

        }
        return (-1);
}