ESP8266 Websocket issue

Question

I realize it might be dumb question, but I've been at it for a few hours and I'm going nowhere. I am trying to figure out the standard Websocket library, however I have an issue casting the uint8_t to a String, so I can work with it easily, how do I do that and is it even possible? What I want to do is, get the payload from the main function as shown in the standard library and give it as a parameter to a function I have. This is the part I need, this is part of the switch statements in the standard library.

void webSocketEvent(uint8_t num, WStype_t type, uint8_t * payload, size_t length) {

   switch(type) {
     case WStype_DISCONNECTED:
     Serial.printf("[%u] Disconnected!\n", num);
   break;
   case WStype_CONNECTED:
    {
      IPAddress ip = webSocket.remoteIP(num);
      Serial.printf("[%u] Connected from %d.%d.%d.%d url: %s\n", num, ip[0], ip[1], ip[2], ip[3], payload);

      // send message to client
      webSocket.sendTXT(num, "Connected");
    }
   break;
   case WStype_TEXT:
      Serial.printf("[%u] get Text: %s\n", num, payload);
      move(payload);

Yes, I have. I have tried with. ` String text = String((char *) &payload[0]); ` and just String text = String(payload); and other ways of trying, this wasn't the first place I stopped at. — Svetlin Yankulov
– Svetlin Yankulov, Commented Nov 5, 2017 at 18:08

Juraj · Accepted Answer · 2017-11-05 19:21:24Z

1

you can't cast it. payload is an array of received bytes and length is the size of received data in that array. if the bytes are characters and you would know that there is one more position allocated in that array, you could put a 0 to payload[length] and by cast to char* it would become a zero terminated string. but you can't know if there is that one byte allocated, so you must copy the payload to your buffer of chars and set a zero at the end.

answered Nov 5, 2017 at 19:21

Juraj♦

18.3k4 gold badges32 silver badges50 bronze badges

Thanks, ended up doing this: char clientCommand[length]; for (uint8_t i = 0; i < length; i++) { clientCommand[i] = payload[i]; } clientCommand[length] = '\0'; Serial.print(clientCommand);

Svetlin Yankulov
– Svetlin Yankulov

2017-11-05 21:13:27 +00:00
Commented Nov 5, 2017 at 21:13

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