Memory heap

holmes4:
@WizenedEE

Not true a simple type is such as int is on the stack, however an instance of a class eg sevro, sreial etc comes in two parts

  1. the data for that instance of the class eg servo1, servo2 which are created on the heap

  2. pointers to the instance data on the heap. The pointers are created on the stack.

You therfore need to free the heap data before the pointer to goes out of scope.

If not the space in the heap remaines allocated but nothing points to it.

Mark

WRONG. This is only true if you allocate the data that way, by using new. Everything else either has a global lifespan (and is never deleted) or block-level scope, and is automatically deleted when you exit the block. You do not have to manually delete it.

Since you bring up those two classes, here are the class declarations for HardwareSerial and Servo. Please point out to us the "pointers to dynamically allocated memory":

class HardwareSerial : public Stream
{
  protected:
    volatile uint8_t * const _ubrrh;
    volatile uint8_t * const _ubrrl;
    volatile uint8_t * const _ucsra;
    volatile uint8_t * const _ucsrb;
    volatile uint8_t * const _ucsrc;
    volatile uint8_t * const _udr;
    // Has any byte been written to the UART since begin()
    bool _written;

    volatile rx_buffer_index_t _rx_buffer_head;
    volatile rx_buffer_index_t _rx_buffer_tail;
    volatile tx_buffer_index_t _tx_buffer_head;
    volatile tx_buffer_index_t _tx_buffer_tail;

    // Don't put any members after these buffers, since only the first
    // 32 bytes of this struct can be accessed quickly using the ldd
    // instruction.
    unsigned char _rx_buffer[SERIAL_RX_BUFFER_SIZE];
    unsigned char _tx_buffer[SERIAL_TX_BUFFER_SIZE];

  public:
    inline HardwareSerial(
      volatile uint8_t *ubrrh, volatile uint8_t *ubrrl,
      volatile uint8_t *ucsra, volatile uint8_t *ucsrb,
      volatile uint8_t *ucsrc, volatile uint8_t *udr);
    void begin(unsigned long baud) { begin(baud, SERIAL_8N1); }
    void begin(unsigned long, uint8_t);
    void end();
    virtual int available(void);
    virtual int peek(void);
    virtual int read(void);
    int availableForWrite(void);
    virtual void flush(void);
    virtual size_t write(uint8_t);
    inline size_t write(unsigned long n) { return write((uint8_t)n); }
    inline size_t write(long n) { return write((uint8_t)n); }
    inline size_t write(unsigned int n) { return write((uint8_t)n); }
    inline size_t write(int n) { return write((uint8_t)n); }
    using Print::write; // pull in write(str) and write(buf, size) from Print
    operator bool() { return true; }

    // Interrupt handlers - Not intended to be called externally
    inline void _rx_complete_irq(void);
    void _tx_udr_empty_irq(void);
};
class Servo
{
public:
  Servo();
  uint8_t attach(int pin);           // attach the given pin to the next free channel, sets pinMode, returns channel number or 0 if failure
  uint8_t attach(int pin, int min, int max); // as above but also sets min and max values for writes. 
  void detach();
  void write(int value);             // if value is < 200 its treated as an angle, otherwise as pulse width in microseconds 
  void writeMicroseconds(int value); // Write pulse width in microseconds 
  int read();                        // returns current pulse width as an angle between 0 and 180 degrees
  int readMicroseconds();            // returns current pulse width in microseconds for this servo (was read_us() in first release)
  bool attached();                   // return true if this servo is attached, otherwise false 
private:
   uint8_t servoIndex;               // index into the channel data for this servo
   int8_t min;                       // minimum is this value times 4 added to MIN_PULSE_WIDTH    
   int8_t max;                       // maximum is this value times 4 added to MAX_PULSE_WIDTH   
};