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Windows API and DLLs --- Part-II |
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| Submitted on: 6/19/2003 7:46:39 AM
By: Deepanjan Datta
Level: Advanced
User Rating:
By 2 Users
Compatibility:VB 3.0, VB 4.0 (16-bit), VB 4.0 (32-bit), VB 5.0, VB 6.0
Users have accessed this article 535 times.
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(About the author) |
| | | Covers nature of DLLs and API data types!!!
API viewer in part III (coming soon)!!! Part I on PSC
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Windows
API - Part II
The
nature of DLLs :
The term Dynamic Link Library has special
implications for programmers. When a routine is said to be said to be linked
dynamically to a program, it means that the routine, whether a subroutine or
a function, is not connected to the program until after the program is compiled.
The function is available at runtime only. The DLL files, however, do not merge
with your program. A program has runtime access to these routines but a
program's EXE file does not contain the physical DLL routines at any time.
API functions never add to the size of your
application's files. During program execution, these routines are loaded just
long enough to run; then, if they are no longer needed the Windows operating
system can free up their resources so that more memory and CPU time is left for
new routines that might start.
Understanding
API data types :
One of the reasons the API routines are difficult
to call is that Windows uses a slightly different set of data types than Visual
Basic. Although Windows API uses 'String' and 'Long' data types, it also uses
other data types such as RECT and MSG.
The 'Alias' keyword is used in 'Declare'
statements to convert some string values that contain illegal characters to
legal Visual Basic equivalents.
Following are some of the data types used
by API routines :
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ANY --- A Windows API routine that
accepts different kinds of data types will list any for those data types.
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ATOM --- Integer data.
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BOOL --- Long integer data.
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CHAR --- Byte data.
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COLOREF --- Long integer data used
specifying color values.
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DWORD --- Long integer data.
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NULL --- Long integer data types used
for uninitialized values.
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LPSTR, LPCSTR --- Matches the String
data type.
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| Other User Comments |
6/19/2003 7:51:04 AM:Deepanjan Datta
Expecting votes and comments ;-))
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6/19/2003 10:31:44 AM:
hmm... Were is the rest of it?
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6/19/2003 12:43:48 PM:me
you can go further and explain more to
us especially with the DLLs
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6/19/2003 4:55:41 PM:Micro X Corp
what does OCX stand for???
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6/20/2003 12:17:28 PM:Jon Williamson
Why ask for comments if you are going
to delete the ones that are negative?
This is a poor excuse for an API
tutorial.
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6/20/2003 2:00:30 PM:Norm Cook
OCX has no literal translation. It
represents the file extension for an
ActiveX OLE Control.
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