实验6 模板类和文件I/O

 实验任务3

task3_1.cpp

 1 #include<iostream>
 2 #include<vector>
 3 template<typename T>
 4 void output(const T&obj){
 5     for(auto &item:obj)
 6     std::cout<<item<<", ";
 7     std::cout<<"\b\b \n";
 8 }
 9 int main()
10 {
11     using namespace std;
12     vector<int> v1;
13     vector<int> v2(5);
14     vector<int> v3(5,42);
15     vector<int> v4{1,9,8,4};
16     vector<int> v5{v4};
17     output(v2);
18     output(v3);
19     output(v4);
20     output(v5); 
21 }

task3_2.cpp

 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     in.read(reinterpret_cast<char *>(&x),sizeof(x));
15     in.close();
16     
17     for(auto i=0;i<N;++i)
18         cout<<x[i]<<", ";
19     cout<<"\b\b \n";
20 }

修改之后的运行结果为：

 char类型一次只读取一个字节长度，int 类型占四个字符的长度，所以改为char后b会在第五个出现。

实验任务4

Vector.hpp

 1 #pragma once
 2 #include<iostream>
 3 using namespace std;
 4 template<typename T>
 5 class Vector{
 6     public:
 7         Vector(int n);
 8         Vector(int n,T value);
 9         Vector(const Vector<T> &x);
10         ~Vector();
11         int get_size(){return size;}
12         T &at(int i){return p[i];}
13         T &operator[](int i){return p[i];}
14         friend void output(Vector &x){
15             for(int i=0;i<x.size-1;i++)
16                  cout<<x.p[i]<<", ";
17             cout<<x.p[x.size-1]<<endl;
18         }
19     private:
20         int size;
21         T *p;
22 };
23 template<typename T>
24 Vector<T>::Vector(int n){
25     size=n;
26     p=new T[n];
27 }
28 template<typename T>
29 Vector<T>::Vector(int n,T value){
30     size=n;
31     p=new T[n];
32     for(int i=0;i<n;i++)
33     p[i]=value;
34 } 
35 template<typename T>
36 Vector<T>::Vector(const Vector<T> &x)
37 {
38     size=x.size;
39     p=new T[size];
40     for(int i=0;i<x.size;i++)
41     {
42         p[i]=x.p[i];
43     }
44 } 
45 template<typename T>
46 Vector<T>::~Vector()
47 {
48     delete [] p;
49 }

task4.cpp

 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 }

运行结果：

 实验任务5

 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 1;
40     }
41     output(out);
42     out.close();    
43 }