Class + Union + Struct = Disaster??

This code example has been causng me no end of trouble.

Some of the errors are included in comments.

//EDIT: I changed the code to working code, but now i get a linker error:

c:\kyle\c++\char map\test.o(.text$initialize__17binary_conversion+0 xee):test.cpp: undefined reference to `binary_conversion::to_hex'

Code:

#include <iostream>

struct char_to_bin {
  unsigned b1: 1;
  unsigned b2: 1;
  unsigned b3: 1;
  unsigned b4: 1;
  unsigned b5: 1;
  unsigned b6: 1;
  unsigned b7: 1;
  unsigned b8: 1;
};

struct char_to_hex {
  unsigned n1: 4;
  unsigned n2: 4;
};

union char_bin_hex {
  char ch;
  struct char_to_bin bits;
  struct char_to_hex hexs;
};

class binary_conversion {
  private:
    union char_bin_hex cbh;
    char ch;
    char binary[9];
    char hexadecimal[5];
    static const char to_hex[] = {'0','1','2','3','4','5',
                            '6','7','8','9','A','B',
                            'C','D','E','F'};

  public:
    binary_conversion(char in_ch){ch = in_ch; initialize();}
   ~binary_conversion(){}
    void  set_ch(char in_ch){ch = in_ch; initialize();}
    void  set_bin(const char in_bin[9]){} // NOT COMPLETED
    void  set_hex(const char in_hex[5]){} // NOT COMPLETED
    char  get_ch(){return ch;}
    char *get_bin(){return binary;}
    char *get_hex(){return hexadecimal;}
  private:
    void initialize(){
      // Create binary string
      sprintf(&binary[0],"%i",cbh.bits.b1);
      sprintf(&binary[1],"%i",cbh.bits.b2);
      sprintf(&binary[2],"%i",cbh.bits.b3);
      sprintf(&binary[3],"%i",cbh.bits.b4);
      sprintf(&binary[4],"%i",cbh.bits.b5);
      sprintf(&binary[5],"%i",cbh.bits.b6);
      sprintf(&binary[6],"%i",cbh.bits.b7);
      sprintf(&binary[7],"%i",cbh.bits.b8);
      binary[8]='\0';
      // Create hex string
      hexadecimal[1]=to_hex[cbh.hexs.n1]; // i think it complains here
      hexadecimal[2]=to_hex[cbh.hexs.n2]; // or here
      hexadecimal[3]='\0';
    }
};

void binary(){
  binary_conversion ch = (char)getche();
  cout << ch.get_bin() << endl;
  cout << ch.get_hex() << endl;
  if (getche());
}

// END EDIT

If anyone could let me know of any problems you see, i would appreciate it greatly.

~Inquirer

• Add ; after the union and struct declarations.
• Declare the structs and unions before the class, to make the class able to use them.

hehe. how silly of me! thanks!

~Inquirer

Now i am getting an odd linker error. See the (edited) original post.

I´m not sure about this but only const data-members of integral type can be initialized within the class body. Try change it to

Code:

//In the class body
//static const char to_hex[] = {'0','1','2','3','4','5', '6','7','8','9','A','B','C','D','E','F'};
static const char to_hex[16];

//And add this to initialize it, outside the class body
const char binary_conversion::to_hex[16]='0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};

Hope that it helps

The only thing i could to to get it to work was make it global. If anyone else has a suggestion, let me know!

~Inquirer