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

#define ERR_MSG(inputs) errMsg((static_cast<std::ostringstream&>(std::ostringstream().flush() << inputs)).str()) // 2
char* errMsg(const std::string& msg)                                 // use with 1 & 2
{
    std::cout << "\nERROR: " << msg << "\n\n";
}

int main()
{
    ERR_MSG("A number: " << 24 << ", a char: " << 'c' << ", that's all!");
}