在本示例中，我们将展示如何使用模板类、文件输入输出以及异常处理。首先定义一个动态数组类，并实现基本的操作和异常处理机制。

#pragma once
#include <iostream>
#include <stdexcept>
using namespace std;

template <typename T>
class DynamicArray {
private:
    int arraySize;
    T* elements;
    template<typename U>
    friend void display(const DynamicArray<U>& arr);

public:
    DynamicArray(int size) {
        if (size < 0) throw length_error("Negative size not allowed");
        elements = new T[size];
        arraySize = size;
    }
    
    DynamicArray(int size, const T& value) {
        if (size < 0) throw length_error("Negative size not allowed");
        elements = new T[size];
        arraySize = size;
        for (int i = 0; i < size; ++i) elements[i] = value;
    }

    ~DynamicArray() {
        delete[] elements;
    }

    int getSize() const { return arraySize; }
    
    T& getElement(int index) const {
        if (index < 0 || index >= arraySize) throw out_of_range("Index out of bounds");
        return elements[index];
    }

    T& operator[](int index) {
        if (index >= arraySize) throw out_of_range("Index out of bounds");
        return elements[index];
    }
};

template<typename U>
void display(const DynamicArray<U>& arr) {
    for (int i = 0; i < arr.getSize(); ++i) {
        cout << arr.getElement(i) << ", ";
    }
    cout << "\b\b " << endl;
}

接下来，我们通过几个测试函数来验证上述类的功能。

#include <iostream>
#include "DynamicArray.hpp"

using namespace std;

void testCase1() {
    int n;
    cout << "请输入数组大小n: ";
    cin >> n;

    DynamicArray<double> arr1(n);
    for (int i = 0; i < n; ++i) arr1.getElement(i) = i * 0.5;
    cout << "arr1: "; display(arr1);

    DynamicArray<int> arr2(n, 33);
    const DynamicArray<int> arr3(arr2);
    cout << "arr2: "; display(arr2);
    cout << "arr3: "; display(arr3);

    arr2[0] = 99;
    arr2[1] = 999;
    cout << "更新后的arr2: "; display(arr2);
    cout << "未变的arr3: "; display(arr3);
}

void testCase2() {
    int n, idx;
    while (cout << "请输入数组大小n和索引idx: ", cin >> n >> idx) {
        try {
            DynamicArray<int> vec(n, n);
            vec.getElement(idx) = -888;
            cout << "vec: "; display(vec);
        } catch (const exception& e) {
            cout << e.what() << endl;
        }
    }
}

int main() {
    cout << "测试案例1: 模板类接口\n";
    testCase1();

    cout << "\n测试案例2: 异常处理\n";
    testCase2();
}

最后，我们还将演示如何使用文件I/O进行数据的读取和写入操作。

#include "Student.hpp"
#include "utils.hpp"
#include <vector>
#include <algorithm>

int main() {
    vector<Student> students;
    load("studentData.txt", students);
    sort(students.begin(), students.end(), compareByMajor);
    output(cout, students);
    save("sortedStudents.txt", students);
    return 0;
}