json非法字符处理 留着备用别忘了

string JsonEscape(const string & s)
{
  unsigned char c;
  string dest;

  for (size_t i = 0; i < s.size(); ++i)  
  {   
    c = s[i]; 
    if ((c == '\\') || (c == '"') || (c == '>')) 
    {   
      dest += '\\'; 
      dest += c;  
    } else if (c == '\b') {
      dest += "\\b"; 
    } else if (c == '\t') {
      dest += "\\t"; 
    } else if (c == '\n') {
      dest += "\\n"; 
    } else if (c == '\f') {
      dest += "\\f"; 
    } else if (c == '\r') {
      dest += "\\r"; 
    } else { 
      if (c < ' ') { 
        std::ostringstream oss;
        oss << "\\u" << std::hex << std::uppercase << std::setfill('0') << std::setw(4) << static_cast<int>(c);
        dest += oss.str();
        
      } else { 
        dest += c;  
      }   
    }   
  }   
  return dest;
}