题单

练习 1：读取一句话并输出
练习 2：按逗号拆分多个单词
练习 3：按空格拆分多个单词
练习 4：输入多行，直到输入 "END" 为止

This is line 1
This is line 2
END

输出：

This is line 1
This is line 2

练习 5：读取学生姓名和成绩（冒号分隔）

Alice:90
Bob:85
Charlie:78

输出：
Name: Alice, Score: 90
Name: Bob, Score: 85
Name: Charlie, Score: 78

升级练习 1：统计每一行有多少个单词

输入示例：

This is a test

C++ is powerful

END

输出示例：

Line 1: 4 words

Line 2: 3 words

升级练习 2：学生信息录入 + 冒号分割 + 成绩排序输出

输入示例：

Alice:88

Bob:95

Charlie:78

输出示例：

Bob 95

Alice 88

Charlie 78

升级练习 3：按分号分割多行内容并过滤指定关键字

输入示例：

hello world;this is a test;nice day

great;test example;sunshine

END

输出示例：(仅输出没有test的句子)

hello world

nice day

great

sunshine

---

---

 代码

1.一句话读入：

#include <iostream>
#include <string>
using namespace std;

int main() {
    string s;
    getline(cin, s); // 读取整行
    cout << "You entered: " << s << endl;
    return 0;
}

2.按逗号拆分单词

#include <iostream>
#include <sstream>
#include <string>
using namespace std;

int main() {
    string s;
    getline(cin, s); // 输入：apple,banana,grape,orange

    stringstream ss(s);
    string word;
    while (getline(ss, word, ',')) { // 按 , 分割
        cout << word << endl;
    }
    return 0;
}

3.按空格：

#include <iostream>
#include <sstream>
#include <string>
using namespace std;

int main() {
    string s;
    getline(cin, s); // 输入：C++ is a powerful language

    stringstream ss(s);
    string word;
    while (ss >> word) { // 按空格自动分割
        cout << word << endl;
    }
    return 0;
}

4.多行输入：

#include <iostream>//多行输入，接着输出
#include <string>
using namespace std;

int main() {
    string line;
    while (getline(cin, line)) {
        if (line == "END") break; // 输入END时停止
        cout << line << endl;
    }
    return 0;
}

#include<iostream>//多行输入，输入完输出
#include<string>
#include<vector>
using namespace std; 

int main() {
    vector<string> s;
    string line;
   
    while ( getline(cin, line)) {
        if(line=="end") break;
		s.push_back(line);
    }
    for (const auto& l : s) {
        cout << l << endl;
    }
    return 0;
}    

5.冒号和换行： 

#include <iostream>
#include <string>
#include <sstream>
#include <vector>

using namespace std;

int main() {
    vector<string> s0;
    string line;
    // 接收全部输入
    while (getline(cin, line)) {
        if (line.empty()) break;
        s0.push_back(line);
    }

    // 处理并输出每行数据
    for (const auto& s : s0) {
        stringstream ss(s);
        string name, score;
        if (getline(ss, name, ':') && getline(ss, score)) {
            cout << "Name: " << name << ", Score: " << score << endl;
        }
    }

    return 0;
}
    

---

升级练习1：

#include <iostream>
#include <string>
#include <sstream>
#include <vector>

using namespace std;

int main() {
    vector<string> s0;
    string line;
    // 接收全部输入
    while (getline(cin, line)) {
        if (line.empty()) break;
        s0.push_back(line);
    }

    vector<int> cnt;// 处理
    for (const auto& s : s0) {
        stringstream ss(s);
        string word;
        
        int count=0;
        while(ss>>word){
        	count++;
		}
		cnt.push_back(count);
    }
	
	for (const auto& i :cnt){
		cout<<i<<"个"<<endl;
	}
	
    return 0;
}
    

升级练习2：

#include <iostream>
#include <sstream>
#include <vector>
#include <algorithm>
using namespace std;

struct Student {
    string name;
    int score;
};

bool cmp(Student a, Student b) {
    return a.score > b.score; // 降序排序
}

int main() {
    string line;
    vector<Student> students;

    while (getline(cin, line)) {
        if (line.empty()) break;

        stringstream ss(line);
        string name,score_str;
        if (getline(ss, name, ':') && getline(ss, score_str)) {
            Student s;
            s.name = name;
            s.score = stoi(score_str);//字符串转换成十进制数字
            students.push_back(s);
        }
    }

    sort(students.begin(), students.end(), cmp);//倒序输出 

    for (const auto& s : students) {
        cout << s.name << " " << s.score << endl;
    }

    return 0;
}

升级练习3：

#include <iostream>
#include <sstream>
#include <string>
using namespace std;

bool contains_test(const string& s) {
    return s.find("test") != string::npos;
}

int main() {
    string line;
    while (getline(cin, line)) {
        if (line == "END") break;

        stringstream ss(line);
        string phrase;
        while (getline(ss, phrase, ';')) {
            if (!contains_test(phrase)) {
                cout << phrase << endl;
            }
        }
    }
    return 0;
}

知识整理与总结归纳：

1.常用搭配：

头文件：sstream\string\vector\algorithm

while(getline(cin,line))//读取并接收输入的每一行

while(getline(ss,line,','))//按照某个特定的符号读取并接受字符串

2.终止条件：

if (line=='end' ) ; if( ! line.empty())

3.字符串与进制数字的转换函数

string a=to_string(365)//a是字符串365

int b=stoi(a,0,n)//将 n 进制的字符串转化为十进制，默认是10

//int b=stoi(a)

4.数据类型检测函数

typeid(变量).name();//在头文件<typeinfo>中