How to send data from ESP8266 to PHP script on website?

Projects Programming
3

OK, so I changed the code around a bit but it still does not verify:

void SendData(int sensor, float temp, float humid)
{
	HTTPClient http;
	String dataline; //Added this to build command outside of GET call
	dataline = "source=" + sensor + "&temp=" + temp + "&humid=" + humid;
	http.begin("http://www.mydomain.com/php/tempreport.php");
	http.addHeader("Content-Type", "application/x-www-form-urlencoded");
	int httpCode = http.GET(dataline);
	if(httpCode != HTTP_CODE_OK)
	{
		SerialDebug.print("Error when sending to server: ");
		SerialDebug.println(httpCode);
	}
}

But I get this error output:

..\DHT_MONITOR.ino:250:34: error: invalid operands of types 'const char*' and 'const char [7]' to binary 'operator+'
  dataline = "source=" + sensor + "&temp=" + temp + "&humid=" + humid;
                                  ^
..\DHT_MONITOR.ino:254:34: error: no matching function for call to 'HTTPClient::GET(String&)'
  int httpCode = http.GET(dataline);

I have seen many examples where one can build strings containing textual representations of variables and tried to use this here, but I don't understand the error messages, can someone please explain what is the problem?