Converting a string to a char array without using extra memory

[Pommie]

If you are going to use the String class, the reason would be that you want to use the operators and functions that the class offers. Otherwise, just stay with a string (i.e., a c string).

The problem is that many libraries return strings and sometimes you need to treat then as C strings so you have no choice in the matter.

Mike.

 

[Pommie]

If your data is simple then you can convert it to json manually. Here's how I send weight, temperature and humidity when requested. It might save some room by not needing the json library.

Mike.

void handleWeight(){
  strcpy(buff,"{");
  sprintf(temp,"\"weight\":\"%.3f\"",scale.get_units());
  strcat(buff,temp);
  sprintf(temp,",\"DHTtemp\":\"%d\"",temp10);
  strcat(buff,temp);
  sprintf(temp,",\"DHThumid\":\"%d\"}",humid10);    //note closing brace
  strcat(buff,temp);
  server.send(200,"application/json",buff);  
}

 

[dr pepper]

I've used sprintf before kinda handy, and I did a json reply with it, but I didnt use strcat(), is that similar to concat().
I have 2 json replys, one for current settings, and another for recorded values to be displayed on a chart, the latter is the trouble.
I might be able to put something together using sprinf to output the char array in a for loop.
I'm dealing with melt temps, melt pressures & drive current, but essentially the same thing.

 

[Pommie]

Yes. strcat() is short for string concatenation.

Mike.