task 3
task 3_1
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 }
task 3_2
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 }
task 3_2 测试截图
改动后
原因分析：
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。
task4
Vector.hpp
1 #include <iostream>
2 using namespace std;
3
4 template<typename T>
5 class Vector {
6 public:
7 Vector(int n, T value);
8 Vector(int n);
9 Vector(const Vector<T> &v);
10 ~Vector();
11
12 int get_size() {return size;}
13 T& at(int n);
14 T& operator[](int n);
15
16 template<typename T1>
17 friend void output(const Vector<T1> &v);
18 private:
19 T *p;
20 int size;
21 };
22 template<typename T>
23 Vector<T>::Vector(int n, T value) {
24 size = n;
25 p = new T[size];
26 for(int i = 0; i < n; i++) {
27 p[i] = value;
28 }
29 }
30
31 template<typename T>
32 Vector<T>::Vector(int n) {
33 size = n;
34 p = new T[size];
35 // for(int i = 0; i < n; i++) {
36 // p[i] = value;
37 // }
38 }
39
40 template<typename T>
41 Vector<T>::Vector(const Vector<T> &v) {
42 size = v.size;
43 p = new T[size];
44 for(int i = 0; i < size; i++) {
45 p[i] = v.p[i];
46 }
47 }
48
49 template<typename T>
50 Vector<T>::~Vector() {
51 delete p;
52 }
53
54 template<typename T>
55 T& Vector<T>::at(int n) {
56 return p[n];
57 }
58
59 template<typename T>
60 T& Vector<T>::operator[](int n) {
61 return p[n];
62 }
63
64 template<typename T1>
65 void output(const Vector<T1> &v) {
66 int n = v.size;
67 for(int i = 0; i < n - 1; i++) {
68 cout << v.p[i] << ", ";
69 }
70 cout << v.p[n - 1] << endl;
71 }
task4.cpp
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 }
运行截图
task 5
task 5.cpp
1 #include <iostream>
2 #include <fstream>
3 #include <iomanip>
4
5 using namespace std;
6
7 void output(ostream &out) {
8 char a[26];
9 //利用字符数组保存26个字母，方便循环时通过直接下标找到相应字母
10 for(int i = 0; i < 26; i++) {
11 a[i] = i + 65;
12 }
13
14 out << " ";
15 for(char c = 'a'; c <= 'z'; c++) {
16 out << " " << c;
17 }
18 out << endl;
19
20 int x;
21 for(int i = 1; i <= 26; i++) {
22 x = 0;
23 out << setw(2) << i;
24 int j = i % 26;
25 for(; x < 26; ) {
26 out << " " << a[j];
27 if(j == 25) j = 0;
28 else j++;
29 x++;
30 }
31 out << endl;
32 }
33 }
34 int main() {
35 output(cout);
36 ofstream out("cipher_key.txt");
37
38 if(!out.is_open()) {
39 cout << "fail to open the file\n";
40 return 1;
41 }
42 output(out);
43
44 out.close();
45 return 0;
46 }
运行截图
标签：文件,int,Vector,实验,template,output,include,模板,size From： https://www.cnblogs.com/youxiasaigao/p/16942628.html