实验六

task3

测试结果：

 

 

 

 

 

 

源代码：

#include <iostream>
#include <fstream>
#include <array>
#define N 5

int main() {
    using namespace std;

    array<int, N> x {97, 98, 99, 100, 101};

    ofstream out;
    out.open("data1.dat", ios::binary);
    if(!out.is_open()) {
        cout << "fail to open data1.dat\n";
        return 1;
    }

    out.write(reinterpret_cast<char *>(&x), sizeof(x));
    out.close();
}

#include <iostream>
#include <fstream>
#include <array>
#define N 5

int main() {
    using namespace std;
    // array<int, N> x;
    array<char,N> x;

    ifstream in;
    in.open("data1.dat", ios::binary);
    if(!in.is_open()) {
        cout << "fail to open data1.dat\n";
        return 1;
    }

    in.read(reinterpret_cast<char *>(&x), sizeof(x));
    in.close();

    for(auto i = 0; i < N; ++i)
        cout << x[i] << ", ";
    cout << "\b\b \n";
    return 0;
}

 原因： 当array数组储存字符型时，读入文件内容”a b c d e f“将把空格也读成字符。

task4

测试结果：

 

源代码：

#pragma once
using std::cout;
using std::endl;
template <typename T>
class Vector
{
private:
    int size;
    T *p;

public:
    Vector(int);
    Vector(int, T);
    ~Vector();
    int get_size() const { return size; }
    T &at(int index)
    {
        return p[index];
    }
    T &operator[](int index)
    {
        return p[index];
    }
    Vector(const Vector<T> &);
    friend void output(Vector &x)
    {
        int i;
        for (i = 0; i < x.size - 1; i++)
        {
            cout << x.p[i] << ", ";
        }
        cout << x.p[i] << endl;
    }
};

template <typename T>
Vector<T>::Vector(int n) : size{n}
{
    p = new T[n];
}

template <typename T>
Vector<T>::Vector(int n, T x) : size{n}
{
    p = new T[n];
    for (auto i = 0; i < n; i++)
    {
        p[i] = x;
    }
}

template <typename T>
Vector<T>::~Vector()
{
    delete[] p;
}

template <typename T>
Vector<T>::Vector(const Vector<T> &vp) : size{vp.size}
{
    p = new T[size];
    for (auto i = 0; i < get_size(); i++)
    {
        p[i] = vp.p[i];
    }
}

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

void test() {
    using namespace std;

    int n;
    cin >> n;
    
    Vector<double> x1(n);
    for(auto i = 0; i < n; ++i)
        x1.at(i) = i * 0.7;

    output(x1);

    Vector<int> x2(n, 42);
    Vector<int> x3(x2);

    output(x2);
    output(x3);

    x2.at(0) = 77;
    output(x2);

    x3[0] = 999;
    output(x3);
}

int main() {
    test();
    return 0;
}

 

task5

测试结果：

 

 

源代码：

#include <iostream>
#include <fstream>
#include <iomanip>
using namespace std;

int main(int argc, char const *argv[])
{
    ofstream outFile;
    outFile.open("cipher_key.txt");
    if (!outFile.is_open())
    {
        cout << "fail to open data1.dat\n";
        return 1;
    }
    for (int i = 0; i < 27; i++)
    {
        if (!i)
        {
            cout << "   ";
            outFile << "   ";
            for (int j = 97; j < 123; j++)
            {
                cout << char(j) << " ";
                outFile << char(j) << " ";
            }
            cout << endl;
            outFile << endl;
            continue;
        }
        cout << setiosflags(ios_base::left) << setw(2) << i << " ";
        outFile << setiosflags(ios_base::left) << setw(2) << i << " ";
        for (int j = i; j < i + 26; j++)
        {
            cout << setiosflags(ios_base::left) << setw(2) << char(65 + j % 26);
            outFile << setiosflags(ios_base::left) << setw(2) << char(65 + j % 26);
        }
        cout << endl;
        outFile << endl;
    }
    outFile.close();
    return 0;
}