#include <string.h>
void binary_search(char key[100], char a[100][100], int n) /*自定義函數binary_search*/
{
int low, high, mid, count = 0, count1 = 0;
low = 0;
high = n - 1;
while (low < high) /*當查找範圍不為0時執行循環體語句*/
{
count++; /*count記錄查找次數*/
mid = (low + high) / 2; /*求出中間位置*/
if (strcmp(key,a[mid])<0) /*當key小於中間值*/
high = mid - 1; /*確定左子表範圍*/
else if (strcmp(key,a[mid])>0) /*當key大於中間值*/
low = mid + 1; /*確定右子表範圍*/
else if (strcmp(key,a[mid])==0) /*當key等於中間值證明查找成功*/
{
printf("success!\nsearch %d times!a[%d]=%d", count, mid, key);
/*輸出查找次數及所查找元素在數組中的位置*/
count1++; /*count1記錄查找成功次數*/
break;
}
}
if (count1 == 0) /*判斷是否查找失敗*/
printf("no found!"); /*查找失敗輸出no found*/
}
main()
{
char key[100],a[100][100];
int i,n;
printf("please input the length of array:\n");
scanf("%d", &n); /*輸入單詞個數*/
printf("please input the element:\n");
for (i = 0; i < n; i++)
scanf("%s", a[i]); /*輸入有序單詞到數組a中*/
printf("please input the number which do you want to search:\n");
scanf("%s", key); /*輸入要查找的關鍵字*/
binary_search(key, a, n); /*調用自定義函數*/
}