实验6 模板类和文件I/O

#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;

    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";
}

运行结果：

 

 修改之后运行结果：

 

 int型数据占四个字节，char类型只占一个字节；97存在第一个字节中，其余三个字节为空，98存在第五个字节中，其余依次类推；以int类型输出，每四字节一输出，所以正常输出97，98，99，100，101；以char类型输出时，每一字节输出一次，第一个字节内存里为97，ASCAII码对应a，后三个字节为空，第五个字节98对应b，所以输出a， ， ， ，b

#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 <class T>
class Vector{
    public:
    Vector(int n):size{n} {p = new T[size]; }
    Vector(int n,T value):size{n} {
        p = new T[size];
        for(int i = 0;i < size; i++)
        p[i] = value;
        }
    ~Vector() {delete []p;}
    Vector(Vector& obj):size{obj.size} {
        p = new T[size];
        for(int i = 0;i < size; i++)
        p[i] = obj.p[i];
     }
    T &at(int i){return p[i];}
    T &operator[](int i) {return p[i];} 
    int get_size() const {return size;}
    private:
    T *p;
    int size;
    friend void output(Vector &x){
        for(int i = 0; i < x.size; i++)
        if(i!=x.size-1) cout << x.at(i) << ",";
        else cout << x.at(i);
        cout << endl;
    }
};

运行结果：

 

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

void output(ostream &out){
    for(int i = 0;i <= 26; i++){
        if(i==0) out << "  ";
        else out << setw(2) << i;
        for(int j = 0; j < 26; j++){
            if(i==0){
                out << " " << (char)('a'+j);
            } 
            else{
                if('A'+i+j<='Z') out << " " << (char)('A'+i+j);
                else out << " " << (char)('A'+i+j-26);
            }
        }
        out << endl;
    }
}
int main(){
    ofstream out;
    output(cout);
    out.open("cipher_key.txt");
    if(!out.is_open()) cout << "error!\n";
    output(out);
    out.close();
    
    
    return 0;
}

运行结果：