Arduino function toCharArray(String, int) not available in PlatformIO

I’m assuming I’m missing a library?

error: 'toCharArray' was not declared in this scope

You might have to share your code for a minimal example that displays the problem. Here’s a sketch I knocked up just now for an Uno. The main file is located in src/main.cpp. If your sketch is in a *.c file then you don’t get Strings.

#include "Arduino.h"

void setup() {

void loop() {
	String aString = "Hello World";
	char aBuffer[15];
	aString.toCharArray(aBuffer, aString.length()+1);



This works fine for me, can you compile this code?

Also, you have to beware of using String variables in Arduino code. This is because there’s only a limited amount of Static RAM and amending Strings is fraught with dynamic memory allocations. It’s best to use char * or char [] wherever “strings” are required. Useful as the String data type is on other platforms with more Static RAM.