Passing 2-Character String

I am trying to pass a 2 character string to a function. The second character of the string must be either P or R.

When executed, the function returns a value of 9999 which indicates that the second character of the string was not a P or R.

I have tried going about this as many ways as I can find, but I am not very adept when it comes to C++. I am using VS 2005 for this.

Here is the code in question:

Code:

/**
	This function converst PS position into Row/Col position
	**/
void PStoRC(int pos, int *result) {
	int  HFunc, HLen, HRc;
	char *HBuff = "AP";

	// set the variables for the convert to R/C function
	HFunc = HA_CONVERT_POS_ROW_COL;
	HLen  = 0x00;
	HRc   = pos;

	// execute the conversion function 
	hllapi(&HFunc, HBuff, &HLen, &HRc); // <- This is where the string is passed

	// get the results
	result[0] = HLen;
	result[1] = HRc;
}

What are reasons that the function would not see the P? The first character identifies a session to apply the function to. This character is identified as I can change it to produce other errors such as invalid session ID. Is there something I'm doing wrong?

Got a prototype for hllapi?

Looks OK to me, so perhaps somewhere else is where the problem is?

--
Mats

Code:

long WINAPI hllapi(LPINT, LPSTR, LPINT, LPINT);

The first variable is a number that identifies a certain "function". That number determines how the other variables are used. So far, everything I have tried has worked up until this fucntion. (The HA_CONVERT_POS_ROW_COL)

I'm not a Windows programmer, or a student of their naming conventions, but I remember seeing a lots of szVarName declarations for pointers to null terminated strings. Is LPSTR the same thing? Have you tried another level of indirection for HBuff, as in &HBuff?

I've tried passing (char *)&HBuff, which I tihnk is pretty much the same as passing HBuff.
It produces compile errors without the type cast.

I have also tried declaring the string in different ways. Making a classic C-Syle array and setting the characters individually, as well as making strings that are NULL terminated.

Since the first character is being identified correctly, I can't imagine what could be wrong out side of a problem with the library. I just kind of find that hard to believe for some reason.

What is HLen? The length of the string you are passing?

Not in the case of this particular HFunc value.

In this case it is passed as a null value and used as a return field for the row.

Well the manual appears to be here (4.5). If you are sure that the result is HARC99_INVALID_CONV_OPT and you are doing everything else as required then probably you might need to seek support from the library providers/support forum...

That's definately the error I am getting. Looks like I will have to seek support for the library. Thanks for all of your help.

Originally Posted by Dino

I'm not a Windows programmer, or a student of their naming conventions, but I remember seeing a lots of szVarName declarations for pointers to null terminated strings. Is LPSTR the same thing? Have you tried another level of indirection for HBuff, as in &HBuff?

LPSTR = char*.
LP means it's a pointer, and STR says it's a string.
Stupid Windows typedefs / conventions.

Originally Posted by shoutatchickens

I've tried passing (char *)&HBuff, which I tihnk is pretty much the same as passing HBuff.
It produces compile errors without the type cast.

Do not use casts!
The compiler is trying to alert you that what you are doing is wrong and the cast only hides it!
Only use casts if you are really, really, really, really sure of what you are doing.

And btw, that prototype is very uninformative.
If you can, do not strip the parameter names: http://cpwiki.sf.net/Don't_remove_parameter_names
Something to think of in the future. Good luck.