undeclared identifier problem

I'm just beginning to learn about moving functions out of the main program.

I've got a BITMAP_FILE_PTR undeclared identifier error in MSVC 6.0 .

I created a header file called bitmapfunct involving BITMAP_FILE_PTR and now I get an error.

I declared the function in my main but how do I make it so it is also declared or defined in the header file ?

Here is the code from my main involving the variable

Code:

typedef struct BITMAP_FILE_TAG
        {
        BITMAPFILEHEADER bitmapfileheader;  // this contains the bitmapfile header
        BITMAPINFOHEADER bitmapinfoheader;  // this is all the info including the palette
        PALETTEENTRY     palette[256];      // we will store the palette here
        UCHAR            *buffer;           // this is a pointer to the data

        } BITMAP_FILE, *BITMAP_FILE_PTR;

do I use extern ?

extern BITMAP_FILE_PTR

?

Can you post the exact code where the problem occurs?

the error happens in the bitmapfunct.h header file. You are right. Sorry here is the code where the error actually occurs.

Code:

/*
header file  bitmapfunct.h
*/

#ifndef bitmapfunct_h
#define bitmapfunct_h

//prototypes



int Load_Bitmap_File(BITMAP_FILE_PTR bitmap, char *filename);
int Unload_Bitmap_File(BITMAP_FILE_PTR bitmap);
int Flip_Bitmap(UCHAR *image, int bytes_per_line, int height);





// FUNCTIONS //////////////////////////////////////////////




/////// load bitmap file function


int Load_Bitmap_File(BITMAP_FILE_PTR bitmap, char *filename)
{
// this function opens a bitmap file and loads the data into bitmap

int file_handle,  // the file handle
    index;        // looping index

UCHAR *temp_buffer = NULL; // used to convert 24 bit images to 16 bit
OFSTRUCT file_data;        // the file data information

// open the file if it exists
if ((file_handle = OpenFile(filename,&file_data,OF_READ))==-1)
   return(0);

// now load the bitmap file header
_lread(file_handle, &bitmap->bitmapfileheader,sizeof(BITMAPFILEHEADER));

// test if this is a bitmap file
if (bitmap->bitmapfileheader.bfType!=BITMAP_ID)
   {
   // close the file
   _lclose(file_handle);

   // return error
   return(0);
   } // end if

I posted a little more than necessary to give you an idea of what is happening.

The error occurs where it says " int Load_Bitmap_File(Bitmap_File_PTR bitmap, char *filename);
"


Trying to break up a program that works by itself into smaller ones with functions so that I can make it bigger and more complex but still readable.

actually, I'm having a lot of problems......



Compiling...
bitmapanim.cpp
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(12) : error C2065: 'BITMAP_FILE_PTR' : undeclared identifier
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(12) : error C2146: syntax error : missing ')' before identifier 'bitmap'
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(12) : error C2059: syntax error : ')'
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(13) : error C2146: syntax error : missing ')' before identifier 'bitmap'
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(13) : error C2059: syntax error : ')'
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(28) : error C2146: syntax error : missing ')' before identifier 'bitmap'
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(28) : error C2086: 'Load_Bitmap_File' : redefinition
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(28) : error C2059: syntax error : ')'
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(29) : error C2143: syntax error : missing ';' before '{'
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(29) : error C2447: missing function header (old-style formal list?)
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(188) : error C2146: syntax error : missing ')' before identifier 'bitmap'
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(188) : error C2086: 'Unload_Bitmap_File' : redefinition
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(188) : error C2059: syntax error : ')'
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(189) : error C2143: syntax error : missing ';' before '{'
c:\program files\microsoft visual studio\myprojects\bitmap anim (broken up)\bitmapfunct.h(189) : error C2447: missing function header (old-style formal list?)

How is the compiler supposed to know what "BITMAP_FILE_PTR " is?
You need to #include the header file containing that definition.

Since you're using other Win32 definitions, you definitely need #include <windows.h>

gg

ok,

question:

If I'm planning on breaking up a program that is a single file and put the functions in other files, do I need classes to do that?

The concept equally applies to regular functions.

Read this thread (and the thread I reference in there).

Post back here if you have any questions.

gg

Move your declaration of your BITMAP_FILE_TAG to bitmapfunct.h

You are misusing header files.

The only things that belong in header files are classes, non-intialized structs, defines, constants, prototypes, etc.

Do not put function bodies in header unless it is an inline function. The rules I follow for inlining functions are: 1. Is is short? - it doesn't do much. 2. Is it called frequently. If 1 and 2 are not true then it is not inlined.

Example:

Matrix.h

Code:

#ifndef _MATRIX_
#define _MATRIX_

#define SUCCESS 0
#define FAILURE -1

class Matrix
{
  protected:
     float *MyMatrix;
     int numrows;
     int numcols;
     int sizeinbytes;
  public:
    Matrix(void) {};
    ~Matrix(void) {if (MyMatrix) delete [] MyMatrix;};
   
    bool Init(int _numrows,int _numcols);
    void Identity(void);
    void Translation(float dx,float dy,float dz);
};

#endif

Matrix.cpp

Code:

#include "Matrix.h"

bool Matrix::Init(int _numrows,int _numcols)
{
  //code here...
}

void Matrix::Identity(void)
{
  //code here....
}

void Matrix::Translation(float dx,float dy,float dz)
{
  //code here....
}

>#ifndef _MATRIX_
>#define _MATRIX_
Leading underscores followed by any upper case letter are reserved by the implementation.

Whatever that means. Anyways use some way to define your headers so that they are not included multiple times.

>Whatever that means.
It means that I can't match your ASM l33tness, so I assert myself by nitpicking your C++. Or it means that leading underscores are error prone and incorrect in standard C++ and you should avoid them. You can pick.

So the actual function body can't be in a header file ?

Ok, well, that is what I was doing wrong then.

Ok...so drop the underscores and do what Prelude says. I'm reading a book right now about C99 but gimme a break the thing is like 900 pages long....so I'm not up on all the standards yet.





No worries...my first program in C totally abused headers. I thought they were simply modules - text files that were combined with the main module to create the program. Header files are simply for placing everything there that normally goes above your function bodies. In other words, your source files will usually only have an include in them and then the function bodies. All of the preliminary stuff like #defines, structs, classes, prototypes, etc. will go into the headers. That's really the simplest explanation I can think of. To avoid namepsace clashes with functions either use classes or namespaces. Yet another explanation is probably begging to be written there...but perhaps not.




Oh and I'm not really as good as some at assembly IMO - I know enough to get the job done.

And for those that think its not necessary I'm using it in Direct3D too. Nothing does extremely fast memory to memory copies like assembly language and that is really what I use it for. Yeah you can use memset....but....I don't. Filling vertex buffers, doing texture to texture writes (in software), etc. are all great spots for assembly. Given that video card resources are scarce your super fast texture to texture write may just be executing in software because the card said.....sorry, charlie, we don't have enough memory or resources for that. Even with all the modern technology you cannot rely on hardware to do everything for you...there's just not enough resources for that yet.