实验一
task1:
代码：
1 #include <iostream> 2 #include <string> 3 #include <vector> 4 #include <algorithm> 5 6 template<typename T> 7 void output(const T &c); 8 9 void test1(); 10 void test2(); 11 void test3(); 12 13 int main() { 14 std::cout << "测试1: \n"; 15 test1(); 16 17 std::cout << "\n测试2: \n"; 18 test2(); 19 20 std::cout << "\n测试3: \n"; 21 test3(); 22 } 23 24 template <typename T> 25 void output(const T &c) { 26 for(auto &i : c) 27 std::cout << i << ' '; 28 std::cout << '\n'; 29 } 30 31 void test1() { 32 using namespace std; 33 34 string s0{"0123456789"}; 35 cout << "s0 = " << s0 << endl; 36 37 string s1(s0); 38 39 reverse(s1.begin(), s1.end()); 40 cout << "s1 = " << s1 << endl; 41 42 string s2(s0.size(), ' '); 43 44 reverse_copy(s0.begin(), s0.end(), s2.begin()); 45 cout << "s2 = " << s2 << endl; 46 } 47 48 49 void test2() { 50 using namespace std; 51 52 vector<int> v0{2, 0, 4, 9}; 53 cout << "v0: "; output(v0); 54 55 vector<int> v1{v0}; 56 reverse(v1.begin(), v1.end()); 57 cout << "v1: "; output(v1); 58 59 vector<int> v2{v0}; 60 reverse_copy(v0.begin(), v0.end(), v2.begin()); 61 cout << "v2: "; output(v2); 62 } 63 64 void test3() { 65 using namespace std; 66 67 vector<int> v0{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}; 68 cout << "v0: "; output(v0); 69 70 vector<int> v1{v0}; 71 72 rotate(v1.begin(), v1.begin()+1, v1.end()); 73 cout << "v1: "; output(v1); 74 75 vector<int> v2{v0}; 76 77 rotate(v2.begin(), v2.begin()+2, v2.end()); 78 cout << "v2: "; output(v2); 79 80 vector<int> v3{v0}; 81 82 rotate(v3.begin(), v3.end()-1, v3.end()); 83 cout << "v3: "; output(v3); 84 85 vector<int> v4{v0}; 86 87 rotate(v4.begin(), v4.end()-2, v4.end()); 88 cout << "v4: "; output(v4); 89 }
运行结果：
问题：
(1 reverse会改变原来的字符串，reverse_copy不会改变
(2 rotate是将一个区间内的元素一个个向某一方向移动，第一和第三个参数代表着区间范围，第二个参数代表方向和距离
task2:
代码：
1 #include <iostream> 2 #include <vector> 3 #include <algorithm> 4 #include <numeric> 5 #include <iomanip> 6 #include <cstdlib> 7 #include <ctime> 8 9 template<typename T> 10 void output(const T &c); 11 12 void test1(); 13 void test2(); 14 15 int main() { 16 std::srand(std::time(0)); 17 std::cout << "测试1: \n"; 18 test1(); 19 20 std::cout << "\n测试2: \n"; 21 test2(); 22 } 23 24 template <typename T> 25 void output(const T &c) { 26 for(auto &i: c) 27 std::cout << i << ' '; 28 std::cout << '\n'; 29 } 30 31 void test1() { 32 using namespace std; 33 34 vector<int> v0(10); 35 generate(v0.begin(), v0.end(), [](){return std::rand()%101;}); 36 cout << "v0: "; output(v0); 37 38 vector<int> v1{v0}; 39 sort(v1.begin(), v1.end()); 40 cout << "v1: "; output(v1); 41 42 vector<int> v2{v0}; 43 sort(v2.begin()+1, v2.end()-1); 44 cout << "v2: "; output(v2); 45 } 46 47 void test2() { 48 using namespace std; 49 50 vector<int> v0(10); 51 generate(v0.begin(), v0.end(),[](){return std::rand()%101;}); 52 cout << "v0: "; output(v0); 53 54 auto min_iter = min_element(v0.begin(), v0.end()); 55 auto max_iter = max_element(v0.begin(), v0.end()); 56 cout << "最小值: " << *min_iter << endl; 57 cout << "最大值: " << *max_iter << endl; 58 59 auto ans = minmax_element(v0.begin(), v0.end()); 60 cout << "最小值: " << *(ans.first) << endl; 61 cout << "最大值: " << *(ans.second) << endl; 62 63 double avg1 = accumulate(v0.begin(), v0.end(), 0.0) / v0.size(); 64 cout << "均值: " << fixed << setprecision(2) << avg1 << endl; 65 66 sort(v0.begin(), v0.end()); 67 double avg2 = accumulate(v0.begin()+1, v0.end()-1, 0.0) / (v0.size()-2); 68 cout << "去掉最大值、最小值之后，均值: " << avg2 << endl; 69 }
运行结果：
问题：
(1 generate能通过第三个参数填充第一、二个参数间的元素
(2 代码更简洁，运行速度更快，只需要遍历一遍就行
(3 两种代码都是使用随机数填充
task3:
代码：
1 #include <iostream> 2 #include <string> 3 #include <algorithm> 4 #include <cctype> 5 6 unsigned char func(unsigned char c); 7 void test1(); 8 void test2(); 9 10 int main() { 11 std::cout << "测试1: 字符串大小写转换\n"; 12 test1(); 13 14 std::cout << "\n测试2: 字符变换\n"; 15 test2(); 16 } 17 18 unsigned char func(unsigned char c) { 19 if(c == 'z') 20 return 'a'; 21 22 if(c == 'Z') 23 return 'A'; 24 25 if(std::isalpha(c)) 26 return static_cast<unsigned char>(c+1); 27 28 return c; 29 } 30 31 void test1() { 32 std::string s1{"Hello World 2049!"}; 33 std::cout << "s1 = " << s1 << '\n'; 34 35 std::string s2; 36 for(auto c: s1) 37 s2 += std::tolower(c); 38 std::cout << "s2 = " << s2 << '\n'; 39 40 std::string s3; 41 for(auto c: s1) 42 s3 += std::toupper(c); 43 std::cout << "s3 = " << s3 << '\n'; 44 } 45 46 void test2() { 47 std::string s1{"I love cosmos!"}; 48 std::cout << "s1 = " << s1 << '\n'; 49 50 std::string s2(s1.size(), ' '); 51 std::transform(s1.begin(), s1.end(), 52 s2.begin(), 53 func); 54 std::cout << "s2 = " << s2 << '\n'; 55 }
运行结果：
问题：
(1 将字符串中的字符都往后一位，z变到a
(2 tolower将所有元素变为大写，toupper将所有元素变为小写
(3 第一、二个参数是要变形的原字符串首位，第三个参数是变形后字符串保存的位置，第四个参数是变形方式；将s2.begin()改成s1.begin()后相当于在原来的字符串上直接修改，不另外保存
task4:
代码：
1 #include <iostream> 2 #include <string> 3 #include <algorithm> 4 5 bool is_palindrome(const std::string &s); 6 bool is_palindrome_ignore_case(const std::string &s); 7 8 int main() { 9 using namespace std; 10 string s; 11 12 while(cin >> s) { 13 cout << boolalpha 14 << "区分大小写: " << is_palindrome(s) << "\n" 15 << "不区分大小写: " << is_palindrome_ignore_case(s) << "\n\n"; 16 } 17 } 18 19 20 bool is_palindrome(const std::string &s) 21 { 22 std::string s1(s); 23 reverse(s1.begin(),s1.end()); 24 return s==s1; 25 } 26 27 bool is_palindrome_ignore_case(const std::string &s) 28 { 29 std::string s1,s2; 30 for(auto c:s) 31 s1 += std::tolower(c); 32 for(auto c:s) 33 s2 += std::tolower(c); 34 reverse(s2.begin(),s2.end()); 35 return s1==s2; 36 }
问题：
使用 std::getline(std::cin, str)
task5：
代码：
1 #include <iostream> 2 #include <string> 3 #include <algorithm> 4 5 std::string dec2n(int x, int n = 2); 6 7 int main() { 8 int x; 9 while(std::cin >> x) { 10 std::cout << "十进制: " << x << '\n' 11 << "二进制: " << dec2n(x) << '\n' 12 << "八进制: " << dec2n(x, 8) << '\n' 13 << "十二进制: " << dec2n(x, 12) << '\n' 14 << "十六进制: " << dec2n(x, 16) << '\n' 15 << "三十二进制: " << dec2n(x, 32) << "\n\n"; 16 } 17 } 18 19 std::string dec2n(int x, int n) 20 { 21 std::string s; 22 int i = 0; 23 char c; 24 if (x == 0) 25 { 26 return "0"; 27 } 28 while (x>0) 29 { 30 if(x%n<10) 31 { 32 c = '0'+x % n; 33 } 34 else 35 { 36 c = 'A' + x % n-10; 37 } 38 x /= n; 39 s += c; 40 i++; 41 } 42 std::reverse(s.begin(), s.end()); 43 return s; 44 }
运行结果：
task6:
代码：
1 #include <iostream> 2 #include <string> 3 #include <iomanip> 4 #include <algorithm> 5 using namespace std; 6 7 int main() 8 { 9 string s; 10 string s1; 11 for (char c = 'a'; c <= 'z'; c++) { 12 s+=c; 13 } 14 cout<<right<<setw(2)<<" "; 15 for(auto c: s) 16 { 17 cout << right << setw(2) <<c; 18 s1 += toupper(c); 19 } 20 cout<<endl; 21 for(int i=1;i<=26;i++) 22 { 23 cout << right << setw(2) << i; 24 rotate(s1.begin(),s1.begin() + 1,s1.end()); 25 for(auto c: s1) 26 { 27 cout << right << std::setw(2) <<c; 28 } 29 cout<<endl; 30 } 31 return 0; 32 }
运行结果：
task7：
代码：
1 #include <iostream> 2 #include <cstdlib> 3 #include <ctime> 4 #include <iomanip> 5 using namespace std; 6 7 char getsign(int sign){ 8 switch(sign){ 9 case 0:return'+'; 10 case 1:return'-'; 11 case 2:return'*'; 12 case 3:return'/'; 13 default: return 0; 14 } 15 } 16 17 int calculate(int sign,int num1,int num2){ 18 switch(sign){ 19 case 0:return num1+num2; 20 case 1:return num1-num2; 21 case 2:return num1*num2; 22 case 3:return num1/num2; 23 default: return 0; 24 } 25 } 26 27 int main() { 28 srand(time(0)); 29 int num1,num2; 30 int count=0; 31 int ans; 32 for(int i=0;i<10;i++){ 33 int sign=rand()%4; 34 bool get = false; 35 while(!get){ 36 num1=rand()%10+1; 37 num2=rand()%10+1; 38 if(sign==1&&num1<num2){ 39 get=false; 40 } 41 else if(sign==3&&num1%num2!=0) 42 get=false; 43 else 44 get=true; 45 } 46 cout<<num1<<getsign(sign)<<num2<<'=' ; 47 cin>>ans; 48 cout<<endl; 49 if(ans==calculate(sign,num1,num2)){ 50 count++; 51 } 52 } 53 cout<<"正确率：" <<fixed<<setprecision(2)<<count/10.00*100<<"%" <<endl; 54 }
运行结果：
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