Arduinization of code

cleaner code using Arduino functionality.
#4

Author: safocl

C_ESR_METER.ino

@@ -865,15 +865,11 @@ void display_Cx_raw(LiquidCrystal_I2C lcd) {
 // or writes default calibration values in first use
 void initEEPROM(void) {
 
-  String flag = String(ESR_METER_FLAG);
-  String flag_read = String("");
-  char c = '\0';
-
+  const char flag[] = ESR_METER_FLAG;
+  char flag_read[sizeof(flag)] = {0};
+  
   // Try to read ESR_METER_FLAG from EEPROM
-  for (uint16_t i = 0; i < flag.length(); i++) {
-    c = EEPROM.read(ESR_METER_FLAG_EEPROM_OFFSET + i);
-    flag_read += c;
-  }
+  EEPROM.get(ESR_METER_FLAG_EEPROM_OFFSET, flag_read);
 
   if (flag == flag_read) {  // Read user settings from EEPROM
     EEPROM.get(U0_ESR_1_EEPROM_OFFSET, U0_ESR_1);
@@ -892,9 +888,7 @@ void initEEPROM(void) {
     EEPROM.put(USR_1_Cx_EEPROM_OFFSET, USR_1_Cx);
 
     // Write ESR_METER_FLAG to EEPROM
-    for (uint16_t i = 0; i < flag.length(); i++) {
-      EEPROM.write(ESR_METER_FLAG_EEPROM_OFFSET + i, flag[i]);
-    }
+    EEPROM.put(ESR_METER_FLAG_EEPROM_OFFSET, flag);
   }
 }