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如何在C++中创建地图功能?

map list c++

yesraaj · 技术社区 · 16 年前

如何在C++中高效地完成这一工作。

5 回复 | 直到 16 年前

jason 16 年前

下面是一个例子:

#include <vector>
#include <iostream>
#include <algorithm>

using namespace std;

int multiply(int);

int main() {
    vector<int> source;
    for(int i = 1; i <= 5; i++) {
    source.push_back(i);
    }

    vector<int> result;
    result.resize(source.size());
    transform(source.begin(), source.end(), result.begin(), multiply);

    for(vector<int>::iterator it = result.begin(); it != result.end(); ++it) {
        cout << *it << endl;
    }
}

int multiply(int value) {
    return value * 10;
}

clstrfsck 8 年前

按照@darids answer的思路,但是C++03(在最初发布时是最新的):

#include <vector>
#include <algorithm>
#include <functional>

std::vector<int> src;
std::vector<int> dst;

std::transform(src.begin(), src.end(),
               std::back_inserter(dst),
               std::bind1st(std::multiplies<int>(), 10));

Edan Maor 16 年前

如果可以使用它,最好的办法可能是使用标准模板库中的函数。

例如,您可能想要签出 for_each transform

John Dibling 16 年前

我发表这篇文章只是为了说明在变换中使用函子而不是全局函数:

#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <functional>
#include <iostream>

using namespace std;

struct MulBy : public std::unary_function<int, int>
{
    MulBy(int v) : v_(v) {}
    int operator()(int lhs) const
    {
        return lhs * v_;
    }
private:
    int v_;
};

int main()
{
    int incoming[5] = {1, 2, 3, 4, 5};
    int result[5] = {0, 0, 0, 0, 0};
    transform(&incoming[0], &incoming[5], &result[0], MulBy(10));
    copy(&result[0], &result[5], ostream_iterator<int>(cout, " "));
    return 0;
}

yesraaj 16 年前

   #include <iostream>
    #include <algorithm>
    #include <vector>
    #include <functional>
    using namespace std;

    struct MulBy : public std::unary_function<int, int>
    {
        MulBy(int v) : v_(v) {}
        int operator()(int lhs) const
        {
            return lhs * v_;
        }
    private:
        int v_;
    };
    int main()
    {
        vector<int> ListOfNumber;
        ListOfNumber.push_back(1);
        ListOfNumber.push_back(2);
        ListOfNumber.push_back(3);
        ListOfNumber.push_back(4);
        ListOfNumber.push_back(5);
        vector<int> ListResult;
        ListResult.resize(ListOfNumber.size());

        //Produces a new list
        transform(ListOfNumber.begin(),ListOfNumber.end(),ListResult.begin(),MulBy(10));
     copy(ListOfNumber.begin(),ListOfNumber.end(),ostream_iterator<int>(cout,"\t"));
        //Modifies the original list
    transform(ListOfNumber.begin(),ListOfNumber.end(),ListOfNumber.begin(),MulBy(10));
    copy(ListResult.begin(),ListResult.end(),ostream_iterator<int>(cout,"\t"));
        cin.get();
    }