1.搜索例子：

[code]#include<iostream>
using namespace std;

/*  美金币值对应的票面名称，给出币值求票面名称
1,	5,	10,	    25,		50
"penny","nickel","dime","quarter","half-dollar"
*/
int search(int key, int arr[], int length)
{
int i;
int ret = -1;
for (i = 0; i < length; i++) {
if (key == arr[i]) {
ret = i;
}
}
return ret;
}

int main(){
int key = 26;
int a[] = { 1,5,10,25,50 };
char *name[] = { "penny","nickel","dime","quarter","half-dollar" };
int j = search(key, a, sizeof(a) / sizeof(a[0]));
if ( j > -1 )
{
printf("%s", name[j]);
}
else {
printf("不存在此面币对应的票面名称！");
}

printf("\n");
system("pause");
return 0;
}

由于分为两个数组存储对cache不友好，故而用结构体对存储结构进行改进（还可以用哈希表）

[code]int a[] = { 1,5,10,25,50 };		//分为两个数组存储对cache不友好
char *name[] = { "penny","nickel","dime","quarter","half-dollar" };

改进后：

[code]#include<iostream>
using namespace std;

/*  美金币值对应的票面名称，给出币值求票面名称
1,	 5,	    10,	  25,	50
"penny","nickel","dime","quarter","half-dollar"
*/

struct {		//用结构体数组存储对cache更友好
int a;
char *name;
} coins[] = {
{1,"penny"},
{5,"nickel"},
{10,"dime"},
{25,"quarter"},
{50,"half-dollar" }
};

int main(){
int key = 25;		//要搜索的币值
int a[] = { 1,5,10,25,50 };		//分为两个数组存储对cache不友好
char *name[] = { "penny","nickel","dime","quarter","half-dollar" };
int i;
for (i = 0; i < sizeof(coins) / sizeof(coins[0]); i++) {
if (key == coins[i].a) {
printf("%s", coins[i].name);
break;
}
}

printf("\n");
system("pause");
return 0;
}

2.选择排序+二分搜索：

二分搜索（英语：binary search），也称折半搜索（英语：half-interval search）、对数搜索（英语：logarithmic search) 。

[code]#include<iostream>
using namespace std;

/*选择排序数组中的数据+二分搜索*/

//二分搜索
int binary_search(int key, int a[], int length);

//求数组中的数据的最大值
int max(int a[], int length);

int main(){
int a[] = { 5,1,6,2,48,16,95,42,53,10,42,39 };
int len = sizeof(a) / sizeof(a[0]);
//选择排序
for (int i = len - 1; i > 0; i--)
{
int maxid = max(a, i + 1);
//swap a[maxid],a[len-1]
int t = a[maxid];
a[maxid] = a[i];
a[i] = t;
}

//输出排序后的数据顺序
for (int i = 0; i < len; i++) {
printf("%d  ", a[i]);
}

printf("\n");

//开始二分搜索
int k;
printf("输入想搜索的数据：");
scanf("%d", &k);
int ret = binary_search(k, a, len);

if (ret > -1) {
printf("%d", ret);
}
else {
printf("不存在%d", k);
}

printf("\n");
system("pause");
return 0;
}

//二分搜索
int binary_search(int key, int a[], int length)
{
int ret = -1;
int left = 0;
int right = length - 1;
while (left <= right) {
int mid = (left + right) / 2;
if (a[mid] == key) {
ret = mid;
break;
}
else if (a[mid] > key) {
right = mid - 1;
}
else {
left = mid + 1;
}
}
return ret;
}

//求数组中的数据的最大值
int max(int a[], int length)
{
int maxid = 0;
int i;
for (i = 1; i < length; i++) {
if (a[i] > a[maxid]) {
maxid = i;
}
}
return maxid;
}