实验1 现代C++基础编程
任务1
- 源代码
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
template<typename T>
void output(const T &c);
void test1();
void test2();
void test3();
int main(){
std::cout << "测试1：\n";
test1();
std::cout << "\n测试2：\n";
test2();
std::cout << "\n测试3：\n";
test3();
}
template <typename T>
void output(const T&c){
for(auto &i : c){
std::cout << i << ' ';
}
std::cout << '\n';
}
void test1(){
using namespace std;
string s0{"0123456789"};
cout << "s0 = " << s0 << endl;
string s1(s0);
reverse(s1.begin(),s1.end());
cout << "s1 = " << s1 << endl;
string s2(s0.size(),' ');
reverse_copy(s0.begin(),s0.end(),s2.begin());
cout << "s2 = " << s2 << endl;
}
void test2(){
using namespace std;
vector<int> v0{2,0,4,9};
cout <<"v0:";output(v0);
vector<int> v1{v0};
reverse(v1.begin(),v1.end());
cout <<"v1:";output(v1);
vector<int> v2{v0};
reverse_copy(v0.begin(),v0.end(),v2.begin());
cout <<"v2:";output(v2);
}
void test3(){
using namespace std;
vector<int> v0{0,1,2,3,4,5,6,7,8,9};
cout <<"v0:";output(v0);
vector<int> v1{v0};
rotate(v1.begin(),v1.begin()+1,v1.end());
cout <<"v1:";output(v1);
vector<int> v2{v0};
rotate(v2.begin(),v2.begin()+2,v2.end());
cout <<"v2:";output(v2);
vector<int> v3{v0};
rotate(v3.begin(),v3.end()-1,v3.end());
cout <<"v3:";output(v3);
vector<int> v4{v0};
rotate(v4.begin(),v4.end()-2,v4.end());
cout <<"v4:";output(v4);
}
-
运行结果截图
![image]()
-
观察与思考
1.reverse是就地反转，而reverse_copy是把反转后的 s0 存进新的数组 s2
任务2
- 源代码
#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <iomanip>
#include <cstdlib>
#include <ctime>
template<typename T>
void output(const T &c);
int generate_random_number();
void test1();
void test2();
int main(){
std::srand(std::time(0));
std::cout << "测试1：\n";
test1();
std::cout << "\n测试2：\n";
test2();
}
template <typename T>
void output(const T &c){
for(auto &i:c)
std::cout << i << ' ';
std::cout << '\n';
}
int generate_random_number(){
return std::rand() % 101;
}
void test1(){
using namespace std;
vector<int> v0(10);
generate(v0.begin(),v0.end(),generate_random_number);
cout << "v0: "; output(v0);
vector<int> v1{v0};
sort(v1.begin(), v1.end());
cout << "v1: "; output(v1);
vector<int> v2{v0};
sort(v2.begin()+1, v2.end()-1);
cout << "v2: "; output(v2);
}
void test2(){
using namespace std;
vector<int> v0(10);
generate(v0.begin(),v0.end(),generate_random_number);
cout << "v0: "; output(v0);
auto min_iter = min_element(v0.begin(),v0.end());
auto max_iter = max_element(v0.begin(),v0.end());
cout << "最小值：" << *min_iter << endl;
cout << "最大值：" << *max_iter << endl;
auto ans = minmax_element(v0.begin(),v0.end());
cout << "最小值：" << *(ans.first) << endl;
cout << "最大值：" << *(ans.second) << endl;
double avg1 = accumulate(v0.begin(),v0.end(),0.0)/v0.size();
cout << "均值："<< fixed << setprecision(2) << avg1 << endl;
sort(v0.begin(),v0.end());
double avg2 = accumulate(v0.begin()+1,v0.end()-1,0.0)/(v0.size()-2);
cout << "去掉最大值、最小值之后，均值: " << avg2 << endl;
}
-
运行结果截图
![image]()
-
观察与思考
1.用于批量填充生成的随机数
2.一个函数干了两个的活
3.效果相同
任务3
- 源代码
#include <iostream>
#include <string>
#include <algorithm>
#include <cctype>
unsigned char func(unsigned char c);
void test1();
void test2();
int main(){
std::cout << "测试1: 字符串大小写转换\n";
test1();
std::cout << "\n测试2: 字符变换\n";
test2();
}
unsigned char func(unsigned char c){
if(c == 'z') return 'a';
if(c == 'Z') return 'A';
if(std::isalpha(c))
return static_cast<unsigned char>(c+1);
return c;
}
void test1(){
std::string s1{"Hello World 2049!"};
std::cout << "s1 = " << s1 << '\n';
std::string s2;
for(auto c:s1)
s2+= std::tolower(c);
std::cout << "s2 = " << s2 << '\n';
std::string s3;
for(auto c: s1)
s3 += std::toupper(c);
std::cout << "s3 = " << s3 << '\n';
}
void test2(){
std::string s1{"I love cosmos!"};
std::cout << "s1 = " << s1 << '\n';
std::string s2(s1.size(),' ');
std::transform(s1.begin(),s1.end(),s2.begin(),func);
std::cout << "s2 = " << s2 << '\n';
}
-
运行结果截图
![image]()
-
观察与思考
1.把当前字母替换成该字母的后一个字母，如果遇上'Z'或'z'就变成'A'或者'a',否则会超出字母表，如果不是字母则原样保留
2.tolower是转小写，toupper是转大写
3.transform(first,end,begin,func)的作用是调用函数func把 [first,end ) 区间内的每个元素改造一下，并将结果写入目标区间（begin是目标区间的起始迭代器）；改动以后就是原地改造元素
任务4
- 源代码
#include <iostream>
#include <string>
#include <algorithm>
bool is_palindrome(const std::string &s);
bool is_palindrome_ignore_case(const std::string &s);
int main() {
using namespace std;
string s;
// 多组输入，直到按下Ctrl+Z结束测试
while(cin >> s) {
cout << boolalpha
<< "区分大小写: " << is_palindrome(s) << "\n"
<< "不区分大小写: " << is_palindrome_ignore_case(s) << "\n\n";
}
}
bool is_palindrome(const std::string &s){
using namespace std;
int len = s.length();
for(int i=0;i<(len/2);i++){
if(s[i]!=s[len-i-1])
return false;
}
return true;
}
bool is_palindrome_ignore_case(const std::string &s){
using namespace std;
int len = s.length();
string s1;
for(auto c: s)
s1 += toupper(c);
for(int i=0;i<(len/2);i++){
if(s1[i]!=s1[len-i-1])
return false;
}
return true;
}
-
运行结果截图
![image]()
-
观察与思考
感觉不知道怎么办，因为空格会直接终止输入，于是向AI求助得到了解决方法，认识了一个新的函数getline
// 使用 getline 读取一行（直到按回车）
while (getline(cin, s)) {
// 这里加个判断，防止空行也输出
if (s.empty()) continue;
cout << boolalpha << "区分大小写：" << is_palindrome(s) << "\n"
<< "不区分大小写：" << is_palindrome_ignore_case(s) << "\n\n";
}
任务5
- 源代码
#include <iostream>
#include <string>
#include <algorithm>
std::string dec2n(int x, int n = 2);
int main() {
int x;
while(std::cin >> x) {
std::cout << "十进制: " << x << '\n'
<< "二进制: " << dec2n(x) << '\n'
<< "八进制: " << dec2n(x, 8) << '\n'
<< "十二进制: " << dec2n(x, 12) << '\n'
<< "十六进制: " << dec2n(x, 16) << '\n'
<< "三十二进制: " << dec2n(x, 32) << "\n\n";
}
}
char get_char(int num){
if (num>=10)return 'A'+(num-10);
return '0'+num;
}
std::string dec2n(int x, int n){
if(x==0) return "0";
std::string s;
while(x != 0){
int m;
m = x % n;
s += get_char(m);
x /= n;
}
reverse(s.begin(), s.end());
return s;
}
- 运行结果截图
![image]()
任务6
- 源代码
#include <iostream>
#include <string>
#include <algorithm>
#include <iomanip>
//模板函数声明
template<typename T>
void output(const T &c){
for(auto &i : c){
std::cout <<std::right<< std::setw(2) << i ;
}
std::cout << '\n';
}
int main(){
using namespace std;
cout << ' ' <<' ';
string s0;
for(char c = 'a';c<='z';c++){
s0+=c;
}
output(s0);
string s1{s0};
int j=0;
for(auto c:s1){
s1[j++] = toupper(c);
};
for(int k=1;k<27;k++){
cout << setw(2) << left << k ;
rotate(s1.begin(),s1.begin()+1,s1.end());
output(s1);
}
}
- 运行结果截图
![image]()
任务7
- 源代码
#include <iostream>
#include <cstdlib>
#include <ctime>
template<typename T>
void output(const T&c){
for(auto i:c) std::cout << i<< ' ';
std::cout << '\n';
}
int main(){
using namespace std;
int result,right=0;
int k=10;
srand(time(0));
while(k>0){
int op = rand()%4;
if(op==0){//+
int a,b,c;
a = (rand()%10+1);
b = (rand()%10+1);
c = a+b;
cout << a << " + " << b << " = ";
cin >> result;
if(result == c){
right++;
}
}
else if(op==1){//-
int a,b,c,t;
a = (rand()%10+1);
b = (rand()%10+1);
if(a<b){
t=a;
a=b;
b=t;
}
c = a-b;
cout << a << " - " << b << " = ";
cin >> result;
if(result == c){
right++;
}
}
else if(op==2){//*
int a,b,c;
a = (rand()%10+1);
b = (rand()%10+1);
c = a*b;
cout << a << " * " << b << " = ";
cin >> result;
if(result == c){
right++;
}
}
else{//除
int a,b,c,t;
a = (rand()%10+1);
b = (rand()%10+1);
if(a%b!=0){
if(a>b){
b=a/b;
c=a/b;
cout << a << " / " << b << " = ";
cin >> result;
if(result == c) right++;
}
else{
a=b/a;
c=b/a;
cout << b << " / " << a << " = ";
cin >> result;
if(result == c) right++;
}
}
else{
c=a/b;
cout << a << " / " << b << " = ";
cin >> result;
if(result == c) right++;
}
}
k--;
}
right = right*10;
cout << "正确率：" << right << "%";
}
- 运行结果截图
![image]()
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