nogod

std::string str; const char * c = str.c_str();

https://deneb21.tistory.com/m/428

https://m.blog.naver.com/twophase/220740359269

https://github.com/esp8266/Arduino/issues/1622

https://tttapa.github.io/ESP8266/Chap07%20-%20Wi-Fi%20Connections.html

https://forum.arduino.cc/index.php?topic=490415.0 http://www.forward.com.au/pfod/ESP8266/GPIOpins/ESP8266_01_pin_magic.html https://www.instructables.com/id/Using-the-4-Pins-of-the-ESP8266-01/ https://randomnerdtutorials.com/esp8266-pinout-reference-gpios/ https://www.forward.com.au/pfod/ESP8266/GPIOpins/ESP8266_01_pin_magic.html https://www.instructables.com/id/ESP0101S-RELAY-..