c++ - 具有多个 vector 的类模板实现

Question

我正在创建一个程序，将数据文件读入一个 vector ，然后显示该 vector 的最小和最大信息。我还必须使用类模板来查找最小值和最大值。我想知道是否有一种方法可以引用任何 vector 而不必专门标记我想使用的两个 vector 。在我下面的代码中，我必须声明 vector v1 才能让我的模板执行最小值和最大值。是否可以为任何载体制作此模板？

    //Nicholas Stafford
//COP2535.0M1 
//Read in text file into multiple vectors and display maximum and minimum integers/strings.

#include <iostream> 
#include <string>
#include <vector>
#include <fstream>
#include <algorithm>


using namespace std;

//Template code area
template <class T>
T min(vector<T> v1)
{
    T lowest = v1[0];
    for (int k = 1; k < 10; k++)
    {
        if (v1[k] < lowest)
            lowest = v1[k];
    }
    return lowest;
}

template <class T>
T max(vector<T> v1)
{
    T highest = v1[0];
    for (int k = 1; k < 10; k++)
    {
        if (v1[k] > highest)
            highest = v1[k];
    }
    return highest;
}


int main() {
    //Number of items in the file
    const int size = 10;
    //Vector and file stream declaration
    ifstream inFile;
    string j; //String for words in data file


    vector<int> v1(size); //Vector for integers
    vector<string> v2(size); //Vector for strings

    //Open data file
    inFile.open("minmax.txt");

    //Loop to place values into vector
    if (inFile)
    {

            for (int i = 0; i < size; i++)
            {
                inFile >> v1[i];
                v1.push_back(v1[i]); //Add element to vector
            }

            cout << "The minimum number in the vector is " << min(v1) << endl;
            cout << "The maximum number in the vector is " << max(v1) << endl;




    }
    else
    {
        cout << "The file could not be opened." << endl;
    }

}

Answer 1

你有一个简单的误解。仅仅因为 min 和 max 的函数参数是 v1 并不意味着你唯一可以调用它的是 v1。实际上，它将是传入的 vector 的本地拷贝，在本地命名为 v1。

#include <vector>
#include <iostream>

template<typename T>
size_t sizeit(std::vector<T> v)  // try changing to v1, v2 and vx
{
    return v.size();  // change to match
}

int main() {
    std::vector<int> v1 { 1, 2, 3, 4, 5 };
    std::vector<float> v2 { 1., 2., 3. };

    std::cout << "v1 size = " << sizeit(v1) << "\n";

    std::cout << "v2 size = " << sizeit(v2) << "\n";
}

现场演示:http://ideone.com/cK13bR