实验六 模板类和文件IO

实验任务3

 1 #include <iostream>
 2 #include <fstream>
 3 #include <array>
 4 #define N 5
 5 
 6 int main() {
 7     using namespace std;
 8 
 9     array<int, N> x {97, 98, 99, 100, 101};
10 
11     ofstream out;
12     out.open("data1.dat", ios::binary);
13     if(!out.is_open()) {
14         cout << "fail to open data1.dat\n";
15         return 1;
16     }
17 
18     out. Write(reinterpret_cast<char *>(&x), sizeof(x));
19     out.close();
20 }
task3_1.cpp
 1 #include <iostream>
 2 #include <fstream>
 3 #include <array>
 4 #define N 5
 5 
 6 int main() {
 7     using namespace std;
 8     array<int, N> x;
 9 
10     ifstream in;
11     in.open("data1.dat", ios::binary);
12     if(!in.is_open()) {
13         cout << "fail to open data1.dat\n";
14         return 1;
15     }
16 
17     in.read(reinterpret_cast<char *>(&x), sizeof(x));
18     in.close();
19 
20     for(auto i = 0; i < N; ++i)
21         cout << x[i] << ", ";
22     cout << "\b\b \n";
23 }
task3_2.cpp

 

 

 对task3_2.cpp的代码稍做改动，把line8的数组类型从int类型修改成char类型，即：array<int, N> x;----> 修改成: array<char, N> x;其它不做任何改动，再次运行程序，运行结果如下：

 

97的ASCLL码值是a，文件里存放的x是整型，在内存占4个字节的空间，把它转换成char字符，a只占1个字节，多出来的3个字节被后面的变量读取，

 

 

实验任务4：

 1 #include <iostream>
 2 #include "Vector.hpp"
 3 
 4 void test() {
 5     using namespace std;
 6 
 7     int n;
 8     cin >> n;
 9     
10     Vector<double> x1(n);
11     for(auto i = 0; i < n; ++i)
12         x1.at(i) = i * 0.7;
13 
14     output(x1);
15 
16     Vector<int> x2(n, 42);
17     Vector<int> x3(x2);
18 
19     output(x2);
20     output(x3);
21 
22     x2.at(0) = 77;
23     output(x2);
24 
25     x3[0] = 999;
26     output(x3);
27 }
28 
29 int main() {
30     test();
31 }
Vector.hpp
 1 #include <iostream>
 2 #include "Vector.hpp"
 3 
 4 void test() {
 5     using namespace std;
 6 
 7     int n;
 8     cin >> n;
 9     
10     Vector<double> x1(n);
11     for(auto i = 0; i < n; ++i)
12         x1.at(i) = i * 0.7;
13 
14     output(x1);
15 
16     Vector<int> x2(n, 42);
17     Vector<int> x3(x2);
18 
19     output(x2);
20     output(x3);
21 
22     x2.at(0) = 77;
23     output(x2);
24 
25     x3[0] = 999;
26     output(x3);
27 }
28 
29 int main() {
30     test();
31 }
task4.cpp

 

 

 实验任务5：

 1 #include<fstream>
 2 #include<iomanip>
 3 #include<iostream>
 4 void output(std::ostream &out){
 5     out << "   ";
 6     for(auto i = 0; i < 26; i++){
 7         out << (char)('a' + i) << ' ';
 8     }
 9     out << std::endl;
10 
11     for(auto i = 1; i <= 26; i++)
12     {
13         out.width(2);
14         out << i ;
15         for(auto j = 0; j < 26; j++)
16         {
17             out.width(2);
18             out << (char)('A' +((i+j)%26));
19         }
20         out << std::endl;
21     }
22        
23 }
24 
25 int main(){
26     using namespace std;
27     
28     output(cout);
29 
30     ofstream out;
31     out.open("cipher_key.txt");
32     if(!out.is_open()){
33         cout<<"fail to open file "<<endl;
34     }
35     output(out);
36     out. close();
37 
38  
39 }
task5.cpp

 

posted @ 2022-12-01 15:31  wch824  阅读(16)  评论(0)  编辑  收藏  举报