实验六 模板类和文件

实验三

task3.1

#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();
}

task3.2

#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";
}

 

 array<int, n=""> x; ----> 修改成: array<char, n=""> x

 

 读取97的ascii码为97，int型占四个字节，<int,5>一共占20个字节，<char,5>占五个字节，所以先输出97对应的a，然后空出三个字节的空再读取下一个98ascii码对应的字母b.

 

实验四

Vector.hpp

#include<cassert>
using namespace std;
template<typename T>
class Vector{
    public:
        Vector(int n) {
        p=new T[n];
        size = n;
    }
    Vector(int n,T value):size{n}{
    p=new T[size];
    for(int i=0;i<size;i++){
        p[i]=value;
        }
    }
    Vector(const Vector<T> &a):size{a.size}{
    p=new T[size];
    for(int i=0;i<size;i++){
        p[i]=a.p[i];
        }
    }
        ~Vector(){
            delete p;
        }
        T &at(int index){
        assert(index>=0&&index<size);
        return p[index];
        }
        int get_size(){
            return size;
        }
        friend void output(Vector &v){
        int i;
        for(i=0;i<v.size-1;i++){
            cout << v.p[i] << ",";
            }
        cout << v.p[i] << endl;
        }
        T& operator[](int i){ //运算符重载 
        return p[i];
        }
    private:
        T size;
        T *p;

};

task4.hpp

#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();
}

 

 

实验五

#include<iostream>
#include<iomanip>
#include<string>
#include<fstream>
using namespace std;
void output(std::ostream &out)
{
    char a[26][26];
    cout<<"  ";
    out<<"  ";
    for(char i='a';i<='z';i++)
    {
        cout<<setw(2)<<setfill(' ')<<i;
        out<<setw(2)<<setfill(' ')<<i;
    }
    cout<<endl;
    out<<endl;
    for(int j=0;j<26;j++)
    {
        cout<<setw(2)<<setfill(' ')<<j+1;
        out<<setw(2)<<setfill(' ')<<j+1;
        for(int k=0;k<26;k++)
        {
            a[j][k]='A'+char((j+k+1)%26);
            cout<<setw(2)<<setfill(' ')<<a[j][k];
            out<<setw(2)<<setfill(' ')<<a[j][k];
        }
        out<<endl;
        cout<<endl;
    }
}
int main()
{
    ofstream out;
    out.open("cipher_key.txt",ios::out);
    if(!out.is_open())
    {
        cout<<"fail to open cipher_ke.text"<<endl;
        return 0;
    }
    output(out);
    out.close();
}