Stupid newbie question

I have recently (last week) restarted programming in C (gcc using Cygwin) after many years of Delphi programming. I am busy looking through code for embedded applications, which I must maintain & develop.

I understand the flow of most of it, but there is one reference in the makefile that I cannot understand, and no amount of googling has answered the question.

What does this mean:

Code:

!include

I know what #include is, and what it does ...

Thanks for your patience.

#include doesn't go into makefiles...
Are you talking about a makefile or a source file? Can you maybe post the entire line (and the ones before and after)?

QuantumPete

Originally Posted by QuantumPete

#include doesn't go into makefiles...
Are you talking about a makefile or a source file? Can you maybe post the entire line (and the ones before and after)?

QuantumPete

Erm - that's why I am confused. The file is definitely the makefile. The compiler used for this code is Borland BCC, v5.02, I believe. And it does compile, as well as make.

Here's a few lines:

Code:

!include $(MAGIC_ROOT)\config.ini

#CODE_SEGMENT 	= 0x4000  
#CODE_SEGMENT 	= 0x6100  
 
CODE_SEGMENT 	= 0x2cca  
#CODE_SEGMENT 	= 0x2a74  
#CODE_SEGMENT 	= 0x2b23  


ROOT_NAME    	= APP
SIGAPPLIB 	   = $(AM)\LIB\am_call.lib    \
                 $(AM)\LIB\pinapi.lib     \
                 $(OS)\lib\os_call.lib    \
            	  $(AM)\LIB\sgl_call.lib   \
            	  $(CTRY)\LIB\sfl_call.lib
.
.
.
.

And there's an equally confusing exclaimation mark later on in the same code snippet:

Code:

# executable without debug
$(EXE_FILE).rom : $(COMMON_LIST) $(SIGAPPLIB) $(APP_OBJ_LIST)
   $(TLINK) $(LINKOPT) @&&!
      $(APP_OBJ_LIST), $(EXE_FILE).rom, $(EXE_FILE).map, $(SIGAPPLIB) $(CC_LIB)
!
  $(HDRTOOL) $(EXE_FILE).rom $(ROOT_NAME).ini +c

That is a makefile (or something like a makefile). It then includes a config.ini from some "magic" place.

The principle is the same as for #include - but since # in makefiles means a comment, you couldn't use #include without breaking old makefiles (which may have #include as a comment somewhere).

--
Mats

Originally Posted by matsp

The principle is the same as for #include - but since # in makefiles means a comment, you couldn't use #include without breaking old makefiles (which may have #include as a comment somewhere).

You learn something new every day.

Originally Posted by matsp

That is a makefile (or something like a makefile). It then includes a config.ini from some "magic" place.

The principle is the same as for #include - but since # in makefiles means a comment, you couldn't use #include without breaking old makefiles (which may have #include as a comment somewhere).

--
Mats

Thank you very much.

Another stupid newbie question ...

I'm used to Pascal/Delphi, which works well with strings.

I have written a function to return to me the hardware platform my app is running on. The function declaration looks like this:

Code:

char* INIT_GetHWType(void)
{
 char* HWType;
 do stuff
 do more stuff
 return HWType;
}

Somewhere else, I'd like to call this function to find out what I have got. So I do this:

Code:

{
   WORD              wTermStatus;
   WORD              wBankResult;
   BYTE                szPin[5];
   
	Storage_Init();

	if (INIT_GetHWType == "xyz")
		{
		//Set display size options here			
	  }

etc., etc., etc.

This gives me a warning : Warning ..\source\init.c 45: Nonportable pointer comparison in function INIT_StartApp()

So I try the following:

Code:

{
   WORD              wTermStatus;
   WORD              wBankResult;
   BYTE                szPin[5];
   char*               HWType;
   
	Storage_Init();

        HWType = INIT_GetHWType;

	if ( HWType== "xyz")
		{
		//Set display size options here			
	  }

etc., etc., etc.

And this gives a compiler error.

Error ..\source\init.c 46: Cannot convert 'char * (*)()' to 'char *' in function INIT_StartApp()

OK, so I've googled this, and vaguely understand what the problem is. What I do not understand is: How do I assign the result of a function (which returns a string) to a variable that contains a string?

In Pascal, I would do something like the following:

Code:

function MyFunction : string;
begin
   do stuff
   result := 'stuff';
end;

procedure Callfunction
var
    astring : string;
begin
    astring := MyFunction;
end;

How do I do the same or similar in C?

You compare stringes with strcmp (INIT_GetHWType, "xyz")
The == doesn't work on strings (pointers to char)

And by INIT_StartApp() you mean INIT_GetHWType()??

Actually, this

Code:

 HWType = INIT_GetHWType;

assigns a the INIT_GetHWType function address to HWType. The compiler moans because HWType is a pointer to char, and INIT_GetHWType is a pointer to a function that returns a char *. My guess is that you want

Code:

 HWType = INIT_GetHWType();

Then of course, you also need to listen to C_ntua's comments on comparing strings.

--
Mats

Thanks. I have found a similar problem with integers ... so your answer makes perfect sense.

Originally Posted by TimL

Thanks. I have found a similar problem with integers ... so your answer makes perfect sense.

It's probably your "pascal" history that plays tricks. In Pascal, the name of a function or procedure on it's own, with no parenthesis is a valid way to call that function or procedure. In C and C++ you ALWAYS need the parenthesis, even if there's no parameters.

I once had (what I thought was) a call to a function in some code, and I couldn't figure out why it wasn't doing what I expected. The compiler didn't give any warnings or anything - it turned out to be that I had written

Code:

func;

instead of

Code:

func();

Since there was no result or parameters, the compiler did just do what I told it: take the address of this function, and don't do anything with it. Which of course wasn't quite what I meant, but the compiler did exactly what I told it to do.

--
Mats

That sounds like what's been happening to me.

Thanks for all your help and explainations, people.

Yet another stupid question ...

What does the double colon do in the following function declaration? I have looked at the Borland C++ language reference, and it talks about the "scope access operator", but I don't understand how that applies here ...

Code:

bool O_Comms::Init (PORT_TYPE port, COMM_PARAM_STRUCT* psComParam)

That has nothing to do with C. That is C++ and has to do with things like classes and namespaces.