C++中string和stringstream怎么使用

在C++中，可以使用string和stringstream来处理字符串。

1. 使用string类来创建和操作字符串：

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello, World!";

    // 获取字符串长度
    std::cout << "Length: " << str.length() << std::endl;

    // 获取子字符串
    std::string subStr = str.substr(0, 5);
    std::cout << "Substring: " << subStr << std::endl;

    // 连接字符串
    std::string concatStr = str + " Welcome!";
    std::cout << "Concatenated string: " << concatStr << std::endl;

    // 查找字符串
    std::size_t found = str.find("World");
    if (found != std::string::npos) {
        std::cout << "Found at index: " << found << std::endl;
    } else {
        std::cout << "Not found" << std::endl;
    }

    return 0;
}

2. 使用stringstream类来处理字符串流：

#include <iostream>
#include <sstream>

int main() {
    std::string str = "42 3.14 Hello";

    std::istringstream iss(str); // 从字符串创建输入流
    int num;
    float fNum;
    std::string word;

    // 从流中提取数据
    iss >> num >> fNum >> word;

    std::cout << "Number: " << num << std::endl;
    std::cout << "Float Number: " << fNum << std::endl;
    std::cout << "Word: " << word << std::endl;

    std::ostringstream oss; // 创建输出流
    oss << "Concatenated: " << num << " " << fNum << " " << word;

    std::cout << oss.str() << std::endl; // 输出流中的字符串

    return 0;
}

这是一些简单的示例，string和stringstream类还有更多的功能和用法，可以根据具体需求查阅C++文档来了解更多信息。