2015级C++第15周程序阅读 范型程序设计

阅读下面的程序，对照运行结果，领会STL的用法
(1)

#include <string>
#include <set>
#include <iterator>
#include <iostream>
using namespace std;
int main()
{
    set <string> strset;
    strset.insert("cantaloupes");
    strset.insert("grapes");
    strset.insert("apple");
    strset.insert("orange");
    strset.insert("banana");
    strset.insert("grapes");
    copy(strset.begin(), strset.end(), ostream_iterator<string>(cout, " "));
    cout << endl;
    return 0;
}

(2)

#include <functional>
#include <numeric>
#include <vector>
#include <iostream>
using namespace std;
int main()
{
    vector<int> v(5);
    for (int i = 0; i < 5; i++)
        v[i] = i + 1;
    int sum = accumulate(v.begin(), v.end(), 0);
    cout << "Sum of values == " << sum << endl;
    int product = accumulate(v.begin(), v.end(), 1, multiplies<long>());
    cout << "Product of values == " << product << endl;
    return 0;
}

(3)

#include <algorithm>
#include <functional>
#include <vector>
#include <iostream>
#include <numeric>
#include <iterator>
using namespace std;
int main()
{
    int a[] = {1,4,7,2,5,8};
    int b[] = {1,2,3,3,2,1};
    const int ASZ = sizeof a / sizeof a[0];
    const int BSZ = sizeof b / sizeof b[0];
    ostream_iterator<int> out(cout,"  ");
    copy(a, a + ASZ, out);
    cout<<endl;
    copy(b, b + BSZ, out);
    cout<<endl;
    int r = accumulate(a, a + ASZ, 0);
    cout << "accumulate 1: " << r << endl;
    // Should produce the same result:
    r = accumulate(b, b + BSZ, 0, plus<int>());
    cout << "accumulate 2: " << r << endl;
    r = inner_product(a, a + ASZ, b, 0);
    // 或  r = inner_product(a, a + ASZ, b, 0, plus<int>(), multiplies<int>());
    cout << "inner_product : " << r << endl;
    int* it = partial_sum(a, a + ASZ, b);
    // 或 int* it = partial_sum(a, a + ASZ, b, plus<int>());
    copy(b, it, out);
    cout<<endl;
    it = adjacent_difference(a, a + ASZ, b);
    // 或 it = adjacent_difference(a, a + ASZ, b, minus<int>());
    copy(b, it, out);
    cout<<endl;
    return 0;
}

(4)

#include <algorithm>
#include <functional>
#include <iostream>
#include <vector>
#include <iterator>
using namespace std;
class myAdd: public binary_function<int,int,int>
{
public:
    int operator()(int a, int b) const
    {
        return a+b;
    }
};
int main()
{
    int a[5]= {1,2,3,4,5};
    vector<int> my(5);
    transform(a,a+5,my.begin(), bind2nd(myAdd(), 4));
    copy(my.begin(), my.end(), ostream_iterator<int>(cout, " "));
    cout<<endl;
    transform(a,a+5,a,my.begin(), myAdd());
    copy(my.begin(), my.end(), ostream_iterator<int>(cout, " "));
    cout<<endl;
    return 0;
}

(5)

#include <iterator>
#include <algorithm>
#include <functional>
#include <iostream>
#include <vector>
using namespace std;
class Angle
{
    int degrees;
public:
    Angle(int deg) : degrees(deg) {}
    int mul(int times)
    {
        return degrees *= times;
    }
};
int main()
{
    int x[] = {1, 2, 4, 5, 8};
    vector<Angle> va;
    for(int i =10; i <= 50; i += 10)
        va.push_back(Angle(i));
    transform(va.begin(), va.end(), x, ostream_iterator<int>(cout , "  "), mem_fun_ref(&Angle::mul));
    cout << endl;
    return 0;
}

(6)

#include <string>
#include <iostream>
#include <map>
using namespace std;
class CStudent
{
public :
    int nStudentID;
    int nAge;
public :
    CStudent()  {  }
    CStudent(int nSID, int nA)
    {
        nStudentID=nSID;
        nAge=nA;
    }
    //复制构造函数
    CStudent(const CStudent& ob) 
    {
        nStudentID=ob.nStudentID;
        nAge=ob.nAge;
    }
};
int main()
{
    map <string, CStudent> mapStudent;
    mapStudent["zhangsan"] = CStudent(100012, 22);
    mapStudent["Lisi"] = CStudent(100085, 21);
    mapStudent["Wangwu"] = CStudent(100093, 23);
    cout << "The Student number for Lisi  is " <<(mapStudent["Lisi"].nStudentID) << endl;
    return 0;
}