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-2

I'm very sorry if this has already been answered somewhere, but after hours of searching, I couldn't find or understand anything.

Being quite new to OOP, I'm exercising myself with classes by trying to create a class where I pre-defined a 2 dimensions character matrix. I keep getting the following error:

error: 'char Matrix2d::keyss [4][4]' is not a static data member of 'class Matrix2d' char Matrix2d::keyss [ROWS][COLS] =

My header is the following:

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:

 char keys [ROWS][COLS];

 private:

;

And My .cpp being this:

char Matrix2d::keys [ROWS][COLS] =


'1','2','3','A',
'4','5','6','B',
'7','8','9','C',
'*','0','#','D'
;

This is a simple code made to run with an arduino keypad.

Thank you in advance for any help and hope I gave enough information as it's my first time posting here.

c++ class arduino

share|improve this question

asked Mar 24 at 15:23

Léo AimoneLéo Aimone

31

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You need an instance of a Matrix2d object to be able to assign to its keys member.
  
  – Jesper Juhl
  Mar 24 at 15:25
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  To initialize your array rather use an initiializer list at your constructor function.
  
  – πάντα ῥεῖ
  Mar 24 at 15:25
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Sorry if some of you have already seen this, but it has been suspended as I was in the wrong topic section
  
  – Léo Aimone
  Mar 24 at 15:28
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  What is the data for? Should there be only one copy of the data during the run-time of the program? Or should each instance (each object) of Matrix2d have its own unique and distinct member variable?
  
  – Some programmer dude
  Mar 24 at 15:32
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Change char keys [ROWS][COLS]; to static char keys [ROWS][COLS]; Review the difference between static and regular data members of a class. en.cppreference.com/w/cpp/language/static
  
  – doug
  Mar 24 at 15:57
  

  
  
  
  

 | 
show 2 more comments

-2

I'm very sorry if this has already been answered somewhere, but after hours of searching, I couldn't find or understand anything.

Being quite new to OOP, I'm exercising myself with classes by trying to create a class where I pre-defined a 2 dimensions character matrix. I keep getting the following error:

error: 'char Matrix2d::keyss [4][4]' is not a static data member of 'class Matrix2d' char Matrix2d::keyss [ROWS][COLS] =

My header is the following:

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:

 char keys [ROWS][COLS];

 private:

;

And My .cpp being this:

char Matrix2d::keys [ROWS][COLS] =


'1','2','3','A',
'4','5','6','B',
'7','8','9','C',
'*','0','#','D'
;

This is a simple code made to run with an arduino keypad.

Thank you in advance for any help and hope I gave enough information as it's my first time posting here.

c++ class arduino

share|improve this question

asked Mar 24 at 15:23

Léo AimoneLéo Aimone

31

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You need an instance of a Matrix2d object to be able to assign to its keys member.
  
  – Jesper Juhl
  Mar 24 at 15:25
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  To initialize your array rather use an initiializer list at your constructor function.
  
  – πάντα ῥεῖ
  Mar 24 at 15:25
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Sorry if some of you have already seen this, but it has been suspended as I was in the wrong topic section
  
  – Léo Aimone
  Mar 24 at 15:28
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  What is the data for? Should there be only one copy of the data during the run-time of the program? Or should each instance (each object) of Matrix2d have its own unique and distinct member variable?
  
  – Some programmer dude
  Mar 24 at 15:32
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Change char keys [ROWS][COLS]; to static char keys [ROWS][COLS]; Review the difference between static and regular data members of a class. en.cppreference.com/w/cpp/language/static
  
  – doug
  Mar 24 at 15:57
  

  
  
  
  

 | 
show 2 more comments

I'm very sorry if this has already been answered somewhere, but after hours of searching, I couldn't find or understand anything.

Being quite new to OOP, I'm exercising myself with classes by trying to create a class where I pre-defined a 2 dimensions character matrix. I keep getting the following error:

error: 'char Matrix2d::keyss [4][4]' is not a static data member of 'class Matrix2d' char Matrix2d::keyss [ROWS][COLS] =

My header is the following:

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:

 char keys [ROWS][COLS];

 private:

;

And My .cpp being this:

char Matrix2d::keys [ROWS][COLS] =


'1','2','3','A',
'4','5','6','B',
'7','8','9','C',
'*','0','#','D'
;

This is a simple code made to run with an arduino keypad.

Thank you in advance for any help and hope I gave enough information as it's my first time posting here.

c++ class arduino

share|improve this question

asked Mar 24 at 15:23

Léo AimoneLéo Aimone

31

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:

 char keys [ROWS][COLS];

 private:

;

char Matrix2d::keys [ROWS][COLS] =


'1','2','3','A',
'4','5','6','B',
'7','8','9','C',
'*','0','#','D'
;

share|improve this question

asked Mar 24 at 15:23

Léo AimoneLéo Aimone

31

share|improve this question

asked Mar 24 at 15:23

Léo AimoneLéo Aimone

31

asked Mar 24 at 15:23

Léo AimoneLéo Aimone

31

asked Mar 24 at 15:23

Léo AimoneLéo Aimone

31

1 Answer
1

active

oldest

votes

1

If the class is defined like that :

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:

 char keys [ROWS][COLS];

 private:

;

that means keys is an attributes of the instance of Matrix2d, but the form

char Matrix2d::keys [ROWS][COLS] =


'1','2','3','A',
'4','5','6','B',
'7','8','9','C',
'*','0','#','D'
;

defines and initializes an attribute of the class Matrix2d, this is incompatible

---

If you want an attribute of the class (a 'static' one) do

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:
 static char keys [ROWS][COLS]; 
;

char Matrix2d::keys [ROWS][COLS] = 
 '1','2','3','A',
 '4','5','6','B',
 '7','8','9','C',
 '*','0','#','D'
;

If you want an attribute of instances having that default value do

class Matrix2d

 public:
 char keys [ROWS][COLS] = 
 '1','2','3','A',
 '4','5','6','B',
 '7','8','9','C',
 '*','0','#','D'
 ;
;

In both case I encourage you to change the visibility

share|improve this answer

answered Mar 24 at 16:16

brunobruno

18.1k31528

add a comment | 

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1

If the class is defined like that :

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:

 char keys [ROWS][COLS];

 private:

;

that means keys is an attributes of the instance of Matrix2d, but the form

char Matrix2d::keys [ROWS][COLS] =


'1','2','3','A',
'4','5','6','B',
'7','8','9','C',
'*','0','#','D'
;

defines and initializes an attribute of the class Matrix2d, this is incompatible

---

If you want an attribute of the class (a 'static' one) do

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:
 static char keys [ROWS][COLS]; 
;

char Matrix2d::keys [ROWS][COLS] = 
 '1','2','3','A',
 '4','5','6','B',
 '7','8','9','C',
 '*','0','#','D'
;

If you want an attribute of instances having that default value do

class Matrix2d

 public:
 char keys [ROWS][COLS] = 
 '1','2','3','A',
 '4','5','6','B',
 '7','8','9','C',
 '*','0','#','D'
 ;
;

In both case I encourage you to change the visibility

share|improve this answer

answered Mar 24 at 16:16

brunobruno

18.1k31528

add a comment | 

1

If the class is defined like that :

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:

 char keys [ROWS][COLS];

 private:

;

that means keys is an attributes of the instance of Matrix2d, but the form

char Matrix2d::keys [ROWS][COLS] =


'1','2','3','A',
'4','5','6','B',
'7','8','9','C',
'*','0','#','D'
;

defines and initializes an attribute of the class Matrix2d, this is incompatible

---

If you want an attribute of the class (a 'static' one) do

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:
 static char keys [ROWS][COLS]; 
;

char Matrix2d::keys [ROWS][COLS] = 
 '1','2','3','A',
 '4','5','6','B',
 '7','8','9','C',
 '*','0','#','D'
;

If you want an attribute of instances having that default value do

class Matrix2d

 public:
 char keys [ROWS][COLS] = 
 '1','2','3','A',
 '4','5','6','B',
 '7','8','9','C',
 '*','0','#','D'
 ;
;

In both case I encourage you to change the visibility

share|improve this answer

answered Mar 24 at 16:16

brunobruno

18.1k31528

add a comment | 

If the class is defined like that :

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:

 char keys [ROWS][COLS];

 private:

;

that means keys is an attributes of the instance of Matrix2d, but the form

char Matrix2d::keys [ROWS][COLS] =


'1','2','3','A',
'4','5','6','B',
'7','8','9','C',
'*','0','#','D'
;

defines and initializes an attribute of the class Matrix2d, this is incompatible

---

If you want an attribute of the class (a 'static' one) do

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:
 static char keys [ROWS][COLS]; 
;

char Matrix2d::keys [ROWS][COLS] = 
 '1','2','3','A',
 '4','5','6','B',
 '7','8','9','C',
 '*','0','#','D'
;

If you want an attribute of instances having that default value do

class Matrix2d

 public:
 char keys [ROWS][COLS] = 
 '1','2','3','A',
 '4','5','6','B',
 '7','8','9','C',
 '*','0','#','D'
 ;
;

In both case I encourage you to change the visibility

share|improve this answer

answered Mar 24 at 16:16

brunobruno

18.1k31528

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:

 char keys [ROWS][COLS];

 private:

;

char Matrix2d::keys [ROWS][COLS] =


'1','2','3','A',
'4','5','6','B',
'7','8','9','C',
'*','0','#','D'
;

const int ROWS = 4;
const int COLS = 4;

class Matrix2d

 public:
 static char keys [ROWS][COLS]; 
;

char Matrix2d::keys [ROWS][COLS] = 
 '1','2','3','A',
 '4','5','6','B',
 '7','8','9','C',
 '*','0','#','D'
;

class Matrix2d

 public:
 char keys [ROWS][COLS] = 
 '1','2','3','A',
 '4','5','6','B',
 '7','8','9','C',
 '*','0','#','D'
 ;
;

share|improve this answer

answered Mar 24 at 16:16

brunobruno

18.1k31528

answered Mar 24 at 16:16

brunobruno

18.1k31528

answered Mar 24 at 16:16

brunobruno

18.1k31528