Pair of functions to read and write values of any type in Arduino's EEPROM memory.

EEPROM_hack.cpp

/*
 Functions to write and restore value of any type in Arduino's EEPROM
 */
#include <EEPROM.h>

// Functions
template <class T> int EEPROM_write(int ee, const T& value)
{
  byte const *p = reinterpret_cast<byte const *>(&value);
  int i;
  for (i = 0; i < sizeof(value); i++)
    EEPROM.write(ee++, *p++);
  return i;
}

template <class T> int EEPROM_read(int ee, T& value)
{
  byte *p = reinterpret_cast<byte *>(&value);
  int i;
  for (i = 0; i < sizeof(value); i++)
    *p++ = EEPROM.read(ee++);
  return i;
}

// Usage
#define VAR1_ADDR 100
#define VAR2_ADDR 200

unsigned int v1;
double v2;

EEPROM_write(VAR1_ADDR, 100);
EEPROM_read(VAR1_ADDR, v1);

EEPROM_write(VAR2_ADDR, 3.14);
EEPROM_read(VAR2_ADDR, v2);