C++语言基础 例程 范型编程简介

曾经的查找

//曾经的查找：顺序查找
#include <iostream>
using namespace std;
int main( )
{
    int d[10]={2,7,4,8,12,1,3,5,9,11},i,key,index=-1;
    cout<<"Input a key you want to search:\n";
    cin>>key;
    for(i=0; i<10; i++)
        if(key == d[i])
        {
            index = i;
            break;
        }
    if(index >= 0)
        cout<<"The index of the key is "<<index<<".\n";
    else
        cout<<"Not found.\n";
    return 0;
}

//曾经的查找：有序表中的二分查找

#include <iostream>
using namespace std;
int main()
{
    int d[10] = {1,3,9,12,32,41,45,62,75,77};
    int low, high,mid,key,index=-1;
    cin>>key;
    low=0,high=9;
    while(low<=high)
    {
        mid=(low+high)/2;
        if(d[mid]==key)
        {
            index=mid;
            break;
        }
        else if(d[mid]>key)
            high=mid-1;
        else
            low=mid+1;
    }
    if(index >= 0)
        cout<<"在："<<index<<".\n";
    else
        cout<<"没有找到.\n";
}

可以这样做

//可以这样做：数组上的find函数
#include <iostream>
#include <algorithm>
using namespace std;
#define SIZE 100
int iarray[SIZE];
int main()
{
    iarray[20] = 50;
    int* ip = find(iarray, iarray + SIZE, 50);
    if (ip == iarray + SIZE)
        cout << "50 not found in array" << endl;
    else
        cout << *ip << " found in array" << endl;
    return 0;
}

//可以这样做：利用向量容器、迭代器、算法
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
vector<int> intVector(100);
int main()
{
    intVector[20] = 50;
    vector<int>::iterator intIter =
        find(intVector.begin(), intVector.end(), 50);
    if (intIter != intVector.end())
        cout << "Vector contains value " << *intIter << endl;
    else
        cout << "Vector does not contain 50" << endl;
    return 0;
}