实验6

task3：

3.1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();
}

3.2代码：

#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;
    }

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

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

运行截图 ：

改为char 运行截图：

分析：int占4个空间，char只占1个空间。存入时97存入1号空间，2到4号空间存0；98存入5号空间；读取时对应1号和5号读取ASCII码为a，b；0为不显示字符。

task4：

Vector.hpp:

#include<iostream>
using namespace std;
template<typename T>
class Vector{
    public:
        
        Vector<T>(int n):size(n){a=new T[n];}
        Vector<T>(int n,int value):size(n){a=new T[n];for(int i=0;i<n;i++) a[i]=value;}
        Vector<T>(T& v):size(v.size){a=new T[size];for(int i=0;i<size;i++) a[i]=v.a[i];}
        ~Vector()=default;
        int get_size(){return size; }
        T& at(int i){return a[i]; }
        T& operator [](int i){return a[i];}
        friend void output(Vector<T> v)
        {
            for(int i=0;i<v.get_size();i++)
            cout<<v.a[i]<<" ";
            cout<<endl;
        }
    private:
        T* a;
        int size;
};

运行截图：

task5：

代码：

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

void output(ofstream& out)
{
    cout<<"   ";
    out<<"   ";
    
    for(int i=0;i<26;i++)
    {
        char ch='a'+i;
        cout<<ch<<" ";
        out<<ch<<" ";
    }
    cout<<endl; out<<endl;
    
    for(int i=0;i<26;i++)
    {
        if(i+1<10){
        cout<<" "<<i+1<<" ";
        out<<" "<<i+1<<" ";}
        else{
            cout<<""<<i+1<<" ";
        out<<""<<i+1<<" ";
        }
        for(int j=i;j<i+26;j++)
        {
            char ch='A'+j%26;
            cout<<ch<<" ";
            out<<ch<<" ";
        }
        cout<<endl; out<<endl;
    }    
}

int main()
{
    ofstream out;
    out.open("cipher_key.txt", ios::out);
    output(out);
}

截图：