arduino example: calling Serial.println() from a C++ source file

serial-print-from-cpp.ino

#include "sub.h"

void setup(){
  Serial.begin(9600);
  delay(0.5 * 1000);
    
  my_log("foo");
}

void loop(){
  my_log("bar");
  delay(1 * 1000);
}

sub.cpp

// sub.cpp

#include <Arduino.h>
#include "sub.h"

void my_log(const char *msg) {
  Serial.println(msg);
}

sub.h

// sub.h

#ifdef __cplusplus
extern "C" {
#endif



void my_log(const char *msg);



#ifdef __cplusplus
}
#endif