The EEPROM::put() method's param doesn't support the type of String or a pointer

[mynameisbill2]

Basic Infos

• This issue complies with the issue POLICY doc.
• I have read the documentation at readthedocs and the issue is not addressed there.
• I have tested that the issue is present in current master branch (aka latest git).
• I have searched the issue tracker for a similar issue.
• If there is a stack dump, I have decoded it.
• I have filled out all fields below.

Platform

• Hardware: [ESP8266]
• Core Version: [Update EEPROM.cpp #6599]
• Development Env: [Arduino IDE]
• Operating System: [Windows]

Settings in IDE

• Module: [Generic ESP8266 Module]
• Flash Mode: [dio]
• Flash Size: [4MB]
• lwip Variant: [v2 Lower Memory]
• Reset Method: [nodemcu]
• Flash Frequency: [40Mhz]
• CPU Frequency: [80Mhz]
• Upload Using: [SERIAL]
• Upload Speed: [115200]

Problem Description

The EEPROM::put() method's param doesn't support the type of String or a pointer. The put() method used sizeof(T), But the sizeof(String)'s output is a const value of 12. So, when the String's length bigger than 12, it failed.

MCVE Sketch

#include <Arduino.h>
#include <EEPROM.h>

String apikey("el2bmjdq45ttqqfrxsy15fx3wyr313t8");

String read__byte_array(unsigned short addr, unsigned short length)                                   
{
  char temp[length];
  for (int i = 0; i < length; i++)
  {
    temp[i] = EEPROM.read(addr + i); //读取数据
  }
  return temp;
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  
  Serial.printf("apikey: %d\n", sizeof(apikey));

  EEPROM.begin(64);

  EEPROM.put(0, apikey);

  EEPROM.end();
  Serial.println("network configruation successfuly saved in EEPROM");

  EEPROM.begin(64);

  String apikey_r = read__byte_array(0, 64);

  Serial.println("=====");
  Serial.println(apikey_r);
}

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

}

Debug Messages

apikey: 12
network configruation successfuly saved in EEPROM
=====
ゑ?/

[devyte]

That is correct, String is an object that is not self contained, similar to STL containers. You have to serialize/deserialize such objects yourself into some contiguous memory block and pass the result to put().
Closing due to not an issue.