Variables Storage in eeprom

Using Arduino Programming Questions
1

I am fairly new to Arduino programming and working on a project where I'm looking to store the variables in the eeprom so I can recall them after reboots. I'm trying to run it on a elegoo uno r3.

First I am uploading the variable structures via a put sketch (below)

/*
  Used to first set up struct for eeprom storage
*/
#include <EEPROM.h>

//User Changed Variables Structure
struct Stored_Variables {
  String Name;
  int Value;
};

Stored_Variables Number_Input = { "Number Input", 10 };
Stored_Variables Pistol_Default = { "Pistol Default", 26 };
Stored_Variables Rifle_Default = { "Rifle Default", 100 };
Stored_Variables Steps_Per_BB = { "Steps Per BB", 339 };

void setup() {
  // put your setup code here, to run once:
  //  Serial.begin(9600);
  //  Serial.println();

  Serial.begin(9600);

  while (!Serial) {

    ;  // wait for serial port to connect. Needed for native USB port only
  }

  
  int eeAddress = 0;  //Location we want the data to be put.

  EEPROM.put(eeAddress, Number_Input);

  Serial.print("Written Number_Input data type! \n\nView the example sketch eeprom_get to see how you can retrieve the values!");

  eeAddress += sizeof(Number_Input);  //Move address to the next byte after float 'f'.

  EEPROM.put(eeAddress, Pistol_Default);

  Serial.print("Written Pistol_Default data type! \n\nView the example sketch eeprom_get to see how you can retrieve the values!");

  eeAddress += sizeof(Pistol_Default);  //Move address to the next byte after float 'f'.

  EEPROM.put(eeAddress, Rifle_Default);

  Serial.print("Written Rifle_Default data type! \n\nView the example sketch eeprom_get to see how you can retrieve the values!");

  eeAddress += sizeof(Rifle_Default);  //Move address to the next byte after float 'f'.

  EEPROM.put(eeAddress, Steps_Per_BB);

  Serial.print("Written Steps_Per_BB data type! \n\nView the example sketch eeprom_get to see how you can retrieve the values!");
}

void loop() {
  // put your main code here, to run repeatedly:
}

Then when trying to read the values back it shows � for the first 2 character on strings and int values are wrong for 3rd and 4th variable. is there something I may have overlooked

Code for Get sketch below

/***

    eeprom_get example.

    This shows how to use the EEPROM.get() method.

    To pre-set the EEPROM data, run the example sketch eeprom_put.

    This sketch will run without it, however, the values shown

    will be shown from what ever is already on the EEPROM.

    This may cause the serial object to print out a large string

    of garbage if there is no null character inside one of the strings

    loaded.

    Written by Christopher Andrews 2015

    Released under MIT licence.

***/

#include <EEPROM.h>

struct Stored_Variables {
  String Name;
  int Value;
};

void setup() {

  Serial.begin(9600);

  while (!Serial) {

    ;  // wait for serial port to connect. Needed for native USB port only
  }

  int eeAddress = 0;  //EEPROM address to start reading from

  Stored_Variables Number_Input;  //Variable to store custom object read from EEPROM.

  EEPROM.get(eeAddress, Number_Input);

  Serial.println("Read Number_Input from EEPROM: ");

  Serial.println(Number_Input.Name);

  Serial.println(Number_Input.Value);

  eeAddress = sizeof(Number_Input);  //Move address to the next byte after float 'f'.

  Stored_Variables Pistol_Default;  //Variable to store custom object read from EEPROM.

  EEPROM.get(eeAddress, Pistol_Default);

  Serial.println("Read Pistol_Default from EEPROM: ");

  Serial.println(Pistol_Default.Name);

  Serial.println(Pistol_Default.Value);

  eeAddress = sizeof(Pistol_Default);  //Move address to the next byte after float 'f'.

  Stored_Variables Rifle_Default;  //Variable to store custom object read from EEPROM.

  EEPROM.get(eeAddress, Rifle_Default);

  Serial.println("Read Rifle_Default.Name from EEPROM: ");

  Serial.println(Rifle_Default.Name);

  Serial.println(Rifle_Default.Value);

  eeAddress = sizeof(Rifle_Default);  //Move address to the next byte after float 'f'.

  Stored_Variables Steps_Per_BB;  //Variable to store custom object read from EEPROM.

  EEPROM.get(eeAddress, Steps_Per_BB);

  Serial.println("Read Steps_Per_BB from EEPROM: ");

  Serial.println(Steps_Per_BB.Name);

  Serial.println(Steps_Per_BB.Value);
}


void loop() {

  /* Empty loop */
}

Serial monitor output

�mber Input

10

Read Pistol_Default from EEPROM:

�stol Default

26

Read Rifle_Default.Name from EEPROM:

�stol Default

26

Read Steps_Per_BB from EEPROM:

�stol Default

26

2

The String class uses dynamically-allocated heap memory to store the actual characters. You can't save a String class variable to EEPROM this way. Make the struct entry a char array.

3

Thanks for your help changing String straight to char solved the problem

4

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