实验六 模板类和文件

实验三

task3.1

 1 #include <iostream>
 2 #include <fstream>
 3 #include <array>
 4 #define N 5
 5 int main() {
 6 using namespace std;
 7 array<int, N> x {97, 98, 99, 100, 101};
 8 ofstream out;
 9 out.open("data1.dat", ios::binary);
10 if(!out.is_open()) {
11 cout << "fail to open data1.dat\n";
12 return 1;
13 }
14 // 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
15 out.write(reinterpret_cast<char *>(&x), sizeof(x));
16 out.close();
17 }

task3.2

 1 #include <iostream>
 2 #include <fstream>
 3 #include <array>
 4 #define N 5
 5 int main() {
 6 using namespace std;
 7 array<int, N> x;
 8 ifstream in;
 9 in.open("data1.dat", ios::binary);
10 if(!in.is_open()) {
11 cout << "fail to open data1.dat\n";
12 return 1;
13 }
14 // 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
15 in.read(reinterpret_cast<char *>(&x), sizeof(x));
16 in.close();
17 for(auto i = 0; i < N; ++i)
18 cout << x[i] << ", ";
19 cout << "\b\b \n";
20 }

 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

 1 #include<cassert>
 2 using namespace std;
 3 template<typename T>
 4 class Vector{
 5     public:
 6         Vector(int n) {
 7         p=new T[n];
 8         size = n;
 9     }
10     Vector(int n,T value):size{n}{
11     p=new T[size];
12     for(int i=0;i<size;i++){
13         p[i]=value;
14         }
15     }
16     Vector(const Vector<T> &a):size{a.size}{
17     p=new T[size];
18     for(int i=0;i<size;i++){
19         p[i]=a.p[i];
20         }
21     }
22         ~Vector(){
23             delete p;
24         }
25         T &at(int index){
26         assert(index>=0&&index<size);
27         return p[index];
28         }
29         int get_size(){
30             return size;
31         }
32         friend void output(Vector &v){
33         int i;
34         for(i=0;i<v.size-1;i++){
35             cout << v.p[i] << ",";
36             }
37         cout << v.p[i] << endl;
38         }
39         T& operator[](int i){ //运算符重载 
40         return p[i];
41         }
42     private:
43         T size;
44         T *p;
45 
46 };

task4.hpp

 1 #include <iostream>
 2 #include "Vector.hpp"
 3 void test() {
 4 using namespace std;
 5 int n;
 6 cin >> n;
 7 Vector<double> x1(n);
 8 for(auto i = 0; i < n; ++i)
 9 x1.at(i) = i * 0.7;
10 output(x1);
11 Vector<int> x2(n, 42);
12 Vector<int> x3(x2);
13 output(x2);
14 output(x3);
15 x2.at(0) = 77;
16 output(x2);
17 x3[0] = 999;
18 output(x3);
19 }
20 int main() {
21 test();
22 }

实验五

 1 #include<iostream>
 2 #include<iomanip>
 3 #include<string>
 4 #include<fstream>
 5 using namespace std;
 6 void output(std::ostream &out)
 7 {
 8     char a[26][26];
 9     cout<<"  ";
10     out<<"  ";
11     for(char i='a';i<='z';i++)
12     {
13         cout<<setw(2)<<setfill(' ')<<i;
14         out<<setw(2)<<setfill(' ')<<i;
15     }
16     cout<<endl;
17     out<<endl;
18     for(int j=0;j<26;j++)
19     {
20         cout<<setw(2)<<setfill(' ')<<j+1;
21         out<<setw(2)<<setfill(' ')<<j+1;
22         for(int k=0;k<26;k++)
23         {
24             a[j][k]='A'+char((j+k+1)%26);
25             cout<<setw(2)<<setfill(' ')<<a[j][k];
26             out<<setw(2)<<setfill(' ')<<a[j][k];
27         }
28         out<<endl;
29         cout<<endl;
30     }
31 }
32 int main()
33 {
34     ofstream out;
35     out.open("cipher_key.txt",ios::out);
36     if(!out.is_open())
37     {
38         cout<<"fail to open cipher_ke.text"<<endl;
39         return 0;
40     }
41     output(out);
42     out.close();
43 }