Stupid newbie question

[TimL]

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:

!include

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

Thanks for your patience.

[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

[TimL]

#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:

!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:

# 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

[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

[QuantumPete]

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.

[TimL]

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.

[TimL]

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:

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:

{
   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:

{
   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:

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?

[C_ntua]

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()??

[matsp]

Actually, this

 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

 HWType = INIT_GetHWType();

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

--
Mats

[TimL]

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

[matsp]

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

func;

instead of

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

[TimL]

That sounds like what's been happening to me.

Thanks for all your help and explainations, people.

[TimL]

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 ...

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

[MacGyver]

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