Undefined reference to class static variable.

Projects Programming
1

Hello.

I am getting undefined references to my static variables.

My code is:
One *.ino file, that has

#include "MainHeader.h"
*****************

void setup()
{

********************
initWebServer();

}

MainHeader.h file has code

#include "MySerial.h"
#include "MyWebServer.h"

MySerial.h:

class MySerial
{

static String log[10];

private:
  /* data */
public:
  MySerial(/* args */);
  ~MySerial();
  void print(String s);

  
};

MySerial::MySerial(/* args */)
{
  for (int x = 0; x < 10; x++)
  {
    MySerial::log[x]="hello "+String(x);
  }
}

MyWebServer.h:

ESP8266WebServer webServer(80);

void initWebServer()
{
    webServer.on(UriBraces("/log"), []() {
        webServer.send(200, "text/html", "");

        for (int x = 0; x < 10; x++)
        {
            webServer.sendContent(MySerial::log[x]);
        }
    });

    // server.on(UriBraces("/rotate/{}/{}/{}"), []() {
    //     String min = server.pathArg(0);
    //     String max = server.pathArg(1);
    //     String direction = server.pathArg(2);

    //     server.send(200, "text/plain", "min = " + min + ", max = " + max);
    // });

    webServer.begin();
    Serial.println("HTTP server started");
}

This code fails to compile:

c:/users/qqq/appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-4-b40a506/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/bin/ld.exe: sketch\SmartToilet.ino.cpp.o:C:\Users\qqq\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.7.4\libraries\ESP8266WebServer\src/ESP8266WebServer-impl.h:524: undefined reference to `MySerial::log'
c:/users/qqq/appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-4-b40a506/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/bin/ld.exe: sketch\SmartToilet.ino.cpp.o:C:\Users\qqq\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.7.4\libraries\ESP8266WebServer\src/ESP8266WebServer-impl.h:525: undefined reference to `MySerial::log'
collect2.exe: error: ld returned 1 exit status

Can you tell me please how to fix this issue?

2

Uh., I just forgot to add String MySerial::log[10]; to MySerial.h.
Solved.

3

This is wrong. You should not instantiate an object in a .h file.

MyWebServer.h:

ESP8266WebServer webServer(80);