Pete's QBASIC Site

I'm working on the sizeof() FUNCTION and I was wondering if you could do a FUNCTION <name> (x AS ANY) where x can really be anything, an integer, a string, etc.

grtz

Why couldn't you?

Let me know how it works out Seb.

All ya gotta do is try it! It probably won't break your machine.

Ted

thx for the reply.

Okay basically sizeof() is suppose to return the bytes of the certain input.

Now here's the tricky part, the input should either be a defined TYPE, an INTEGER, a LONG, a SINGLE, a DOUBLE, or a STRING. Nicest thing is, sizeof() is a build in OPERATOR/FUNCTION in C, so I can't get an exact location of its source code. Atleast the STRING-part, it simple because we just us LEN already for that.

I've tried to DECLARE FUNCTION sizeof(x AS ANY) but that only seems to work for TYPE when the FUNCTION sizof(x AS DeclareType) is. So it doesn't work just like that.

I had the idea of making several sizeof() functions:

• FUNCTION sizeofdouble(x AS DOUBLE)
  FUNCTION sizeofint(x AS INTEGER)
  FUNCTION sizeoflong(x AS LONG)
  FUNCTION sizeofsingle(x AS SINGLE)
  FUNCTION sizeofstring(x AS STRING)
  FUNCTION sizeoftype(x AS ANY) <- still tricky

So the only working code I have is for a sizeof() a string.

Grtz

Here are the byte sizes in QB:

Integer = 2 bytes = 16 bits 'thus you can store 2 values in AH and AL
Long = 4 bytes = 32 bits
Single = 4 bytes = 32 bits
Double = 8 bytes = 64 bits

That is how you determine the size of a TYPE declaration for file records or headers.

Ted

LEN() also shows the number of bytes needed by the variable.

Never tried that. I thought it only did strings. Nice to know!

Ted

I just wonder what coding problem you have that requires to know the length of a variable (except string)

If I create a TYPE, for example, and put a bunch of variables, I never needed to need the size. QBasic worries about that.

At the end, I create a record, say XXX as that TYPE.

Fine, now I might finally need the size, so I say LEN(XXX).

I never knew how long a single was, or cared.

Just wondering...

Thx for the replies guys!

Burger, that's really handy! Pats, also handy, and I'll try that one for sure!. Mac could you explain that type thing more? Basicially I do: I'll keep you guys updated on the progress.

Here's an example of a type: The Type definition is used to get the file information back from DOS. There are 43 bytes of information you can get with an Interrupt Routine. To find out how many bytes are in the TYPE DTA variable use LEN(DTA).

Type is similar to an array that holds different types of data. For example the filename is held in the DTA.Named variable. It uses 13 bytes because DOS adds a CHR$(0) to the end of the file name.

Types are often used to define a record in Random files also. Random file records would be the LEN of the Type and the number of records is:

NumberOfRecords = LEN(DTA) \ LOF(#)

In the OPEN RANDOM Statement. LEN = LEN(DTA) 'That includes number lengths also.

The length of a TYPE declaration can also come in handy as when working on bitmaps. The offset tells you where the palette and picture information is located AFTER the Header information.

Ted

Sorry for not replying before. I meanted to ask how Mac calculated the LEN of his TYPE's.

Nevertheless is your info, Ted, very handy though.

Thx

Patz:

I could not get QB 4.5 to accept any of your code, as in: I was able to use: Am I doing something wrong?

A variable name is used with LEN. It needs a value NOT 0. PRINT LEN(num) displays nothing! Also INT is a QB function and should be used as such. PATZ just used that as an example.

You have to use a variable when getting lengths of numbers! LEN(200) will not work!
QB requires variables with LEN when checking numbers.

Ted

Ted, once again thx for the insight on this matter.