Passing parameters to DLL function

[mensud]

Hello,

I want to use a function from DLL which was developed in VC++. This function receive two parameters (SHORT data type) as hexadecimal numbers. I don't know how to pass the next sequence of characters "^XA,P,P,P,^FS" to this function, as one of parameters. I mean, how to convert this sequence as an array of hexadecimal numbers?

By the way, I can't pass the whole char sequence to this function. Instead, I have to pas char by char.

Thanks in advance

Mensud

 

[DSummZZZ]

?Right(Transform(Asc('^'), '@0x'), 2)
Will give you a hex representation of the "^" character, if that is what you need.
?ASC('^') will give you the ascii value, which may be what the function actually requires.

To pass it, you may need to do something like:
DECLARE INTEGER MyDLL IN 'SomeLib' SHORT @Parm1

Then call it using:
Parm1 = Right(Transform(Asc('^'), '@0x'), 2)
?MyDLL(@Parm1)

-or-

Parm1 = Asc('^')
?MyDLL(@Parm1)



-Dave S.-

Even more Fox stuff at:

http://www.davesummers.net/foxprolinks.htm

 

[mensud]

Thanks Dave for your response.

What I am trying is to print to parallel port (windows 2000)
I declared my function Out32 as:

declare integer Out32 in "spports32.dll" as "Out32" short @PortAddress, short @PortString

The first parameter is hex address of the parallel port (0x378), and second parameter is "some" string (hexadecimal).
Here is how I call the function:

...
cString='^XA^PRA,A,A'
parm1=right(transform(asc(substr(cString,1)),'@0x'),2)
*-- For now I take only first character '^' which is 5E hex
*-- now I call function as:

=out32(378,@parm1)

But I get error message: Data type mismatch. Why?

 

[rgbean]

Normally you only need the @ in the Declare and call if you are returning values through these paramaters. SHORT and a character string longer than two bytes doesn't make sense - a SHORT is only 16 bits long.

Note: 0x378 isn't the same as 378.

I'd try something like:

declare integer Out32 in "spports32.dll" as "Out32" short PortAddress, short PortChar

= out32(0x378, 0x5E)

Rick

 

[AirCon]

mensud,

As an addition to Rick's comment, when you declare it short, you must pass in a numeric value. You cannot pass in STRING into SHORT. That's the reason you get data type mismatch.

-- AirCon --

 

[mensud]

OK, I made stupid mistake.

But how to convert character '^' (0x5E) to hexadecimal and pass it into function. If I use parm1 as Dave suggested, I obviously get an error because of mismatched types, but how to pass hex value, not integer.
I am totally confused.

Anyway thanks for your help.

Mensud

 

[AirCon]

mensud,

But how to convert character '^' (0x5E) to hexadecimal and pass it into function

Sorry, I don't eaxactly sure what do you want.
- If you want to pass it as a numeric (SHORT). You can just pass 0x5E or 94.
- If you want to pass it as a char/string just pass it chr(0x5E) but you have to declare as STRING in the declaration
- If you want to pass it as hex but in form of string use what Dave's had suggested. Also you have to declare as STRING


-- AirCon --

 

[DSummZZZ]

There is no hex data type in VFP, only a character representation of hex, as in 0x0000005E. Simply because VFP doesn't see an 'E' as a value. It sees it as a character.
You can get the value of it like this:
?VAL('0x0000005E')
But, if you pass ASC('^'), you should get the value you need passed.


-Dave S.-

Even more Fox stuff at:

http://www.davesummers.net/foxprolinks.htm

 

[rgbean]

Dave,
All these are equivalent:

? VAL('0x0000005E') && Actually INT(VAL('0x0000005E'))
? 0x5e
? asc('^')
? 94

Each has the same "value", they are just different ways of representing the concept of ninty-four.

As my partner has often said "Bits is Bits"!

Rick

 

[DSummZZZ]

Rick,

That's kinda what I was trying to ellude to, it just didn't come out right.
By passing VAL('0x0000005E') or ASC('^'), the same value gets passed 'on the inside'.



-Dave S.-

Even more Fox stuff at:

http://www.davesummers.net/foxprolinks.htm

 

[mensud]

Problem solved.

Thanks to everybody.

Mensud