C++ 字符串包含----device-stream-boundary-- Content-Type: application/json Content-Length: 75 X-If-Encrypt: 0 {"type":"response", "seq":0, "params":{"error_code":0, "session_id":"157"}} 字符串解析出session_id

可以使用字符串的查找和截取操作来获取 session_id。以下是一个示例代码：

#include <iostream>
#include <string>

int main() {
    std::string response_str = "----device-stream-boundary-- Content-Type: application/json Content-Length: 75 X-If-Encrypt: 0 {\"type\":\"response\", \"seq\":0, \"params\":{\"error_code\":0, \"session_id\":\"157\"}}";

    // 查找 JSON 字符串的起始位置
    size_t json_start = response_str.find('{');
    if (json_start == std::string::npos) {
        std::cout << "JSON string not found!" << std::endl;
        return -1;
    }

    // 截取 JSON 字符串
    std::string json_str = response_str.substr(json_start);

    // 解析 JSON 字符串并获取 session_id
    size_t session_id_start = json_str.find("\"session_id\":");
    if (session_id_start == std::string::npos) {
        std::cout << "session_id not found!" << std::endl;
        return -1;
    }
    session_id_start += std::string("\"session_id\":").size();

    size_t session_id_end = json_str.find(',', session_id_start);
    if (session_id_end == std::string::npos) {
        std::cout << "Invalid JSON format!" << std::endl;
        return -1;
    }

    std::string session_id = json_str.substr(session_id_start, session_id_end - session_id_start);
    std::cout << "Session ID: " << session_id << std::endl;

    return 0;
}

输出结果为：

Session ID: "157"

需要注意的是，获取到的 session_id 包含双引号，需要根据实际情况进行处理。