实验6

TASK3:

#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;
    }
    // 把从地址&x开始连续sizeof(x)个字节的数据块以字节数据块方式写入文件data1.txt
    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;
    ifstream in;
    in.open("data1.dat", ios::binary);
    if (!in.is_open()) {
        cout << "fail to open data1.dat\n";
        return 1;
    }
    // 从文件流对象in关联的文件data1.dat中读取sizeof(x)字节数据写入&x开始的地址单元
    in.read(reinterpret_cast<char*>(&x), sizeof(x));
    in.close();
    for (auto i = 0; i < N; ++i)
        cout << x[i] << ", ";
    cout << "\b\b \n";
}

改动之后结果如图所示，首先内存是连续储存的，int类型占4个字节，char类型占1个，储存就空的部分自动补零，所以一开始97，输出a，而a之后连续三个内存0，所以输出错误，第五个内存单元则储存98，输出b

TASk4:

#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();
}

 

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

template <typename T>
class Vector
{
public:
    Vector(int n)
    {
        size = n;
        t = new T[n];
    }
    Vector(int n, T a)
    {
        size = n;
        t= new T[n];
        for (int i = 0; i < n; i++)
        {
            t[i] = a;
        }
    }
    T& at(int n)
    {
        return t[n];
    }
    T& operator[](int n)
    {
        return t[n];
    }
    int getsize()
    {
        return size;
    }

private:
    int size;
    T* t;
};
template <typename T>
void output(Vector<T>& t)
{
    for (int i = 0; i < t.getsize(); i++)
        cout << t[i] << ' ';
    cout << endl;
}

Task5:

#include<iostream>
#include <fstream>
#include <iomanip>
using namespace std;
void output(std::ostream& out);
int main() {
    ofstream f;
    f.open("cipher_key.txt");
    if (!f.is_open()) {
        cout << "fail to open file " << "cipher_key" << endl;
    }
    output(f);
    f.close();
    output(cout);

}
void output(std::ostream& out) {
    char code[30];
    char Code[30];
    for (int i = 0; i < 26; i++) {
        code[i] = 'a' + i;
    }
    out << "    ";
    for (int i = 0; i < 26; i++) {
        out << code[i] << " ";
    }
    out << "\n";
    for (int i = 1; i <= 26; i++) {
        for (int t = 0; t < 26; t++) {

            if (t + i <= 25) {
                Code[t] = 'A' + t + i;
            }
            else if (t + i > 25) {
                Code[t] = 'A' + t + i - 25 - 1;
            }
        }
        out << setw(2) << i << " ";
        for (int t = 0; t < 26; t++) {
            out << Code[t] << " ";
        }
        out << "\n";

    }
}