字符串拼接后运行报错。

#include <iostream>
#include <string>

using namespace std;

int main()
{
    int saveImageCount = 123;
    int rtkEventCount = 123;

    string strSend ="{\n\t" "\"imageCount\"" + ':' + std::to_string(saveImageCount) + ',' + "\n\t" +
                    "\"rtk-eventCount\"" + ':' + std::to_string(rtkEventCount)  + ',' + "\n" + "}";

    cout << strSend << endl;

    return 0;
}

运行如下:

$ ./manual-json

_M_construct null not valid123,
        "rtk-eventCount":123,
}

修复:

用变量替换 "\"imageCount\"" 。

int main()
{
    int saveImageCount = 123;
    int rtkEventCount = 123;
    string image = "imageCount";

    string strSend ="{\n\t\"" + image + "\":" + std::to_string(saveImageCount) + ',' + "\n\t" +
                    "\"rtk-eventCount\"" + ':' + std::to_string(rtkEventCount)  + ',' + "\n" + "}";

    cout << strSend << endl;

    return 0;
}

运行如下:

$ ./manual-json

{
        "imageCount":123,
        "rtk-eventCount":123,
}