by Rob Loach (2 Submissions)
Category: Data Structures
Compatability: Visual Basic 5.0
Difficulty: Intermediate
Date Added: Wed 3rd February 2021
Rating: 
(3 Votes)
Learn how to not only create a DLL file, but also add it to another project, and call its functions, subs, and properties. This tutorial is step-by-step and very easy to understand. I made this because I noticed that all the other how-to DLL examples on VBC were pretty poor.
VBcoders
DLL Tutorial: MyFirstDLL
Author: Rob Loach
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In this tutorial you will learn:
tab-stops:list 54.0pt'>[if !supportLists]·
[endif]How to make a DLL file.
tab-stops:list 54.0pt'>[if !supportLists]·
[endif]How to call the DLL from a different project.
tab-stops:list 54.0pt'>[if !supportLists]·
[endif]How to make a class with properties, subs, and
functions.
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Welcome
Welcome to my tutorial,
MyFirstDLL. If you read through this
tutorial, and do all the coding, it will take you about 3-10 minutes for you to
fully understand how the DLL system in VB works.
information is bolded. The goal of
this tutorial is to explain step-by-step how to create and use a DLL file.
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What is a DLL?
A DLL is a file that you
can have your application use. A
programmer can use the functions in a DLL file, but the code itself cannot be
accessed. This allows you to make
various things such as game engines.
You can then distribute the engine to the public without actually giving
out the code. DLLs are very useful
because it allows you to hold a large amount of code in only one file.
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So how do I make a DLL file?
To make a DLL, follow
these simple steps:
[endif]Open
Microsoft Visual Basic.
[endif]Goto
File
Roman";mso-char-type:symbol;mso-symbol-font-family:
Wingdings'>
New Project.
[endif]Start
an ActiveX DLL.
[endif]This
new window is your DLL. You currently
only have one object in it, a class.
Now it is time to put in the code that you want your DLL to use.
code.
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mso-padding-alt:0cm 5.4pt 0cm 5.4pt'>
New";color:green'>'=====================
of
class
Now you can type CLASS and . and
appear.
New";color:green'>'=====================
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New"'>
New"'>p_Text
As String
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!supportEmptyParas] [endif]
New"'>
Text() As String
Text =
p_Text
color:blue'>
Text(ByVal i_Text
As String)
p_Text
= i_Text
color:blue'>
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New"'>
color:blue'>
MsgBox
p_Text, vbOKOnly, "DLL Function Called"
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This is your class file inside
your new DLL. All it will do is
hold a string called p_Text. Calling
the property named Text can change the string.
When the DisplayMsg sub is called, it will make a messagebox saying the
Text string.
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You could put any code you want
into this class. This is just an example
that we will be using. You can put
anything you want into the DLL file (Forms, Classes, Modules, etc).
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[endif]Now
you have to rename your class file.
For this example, name it clsMyFirstDLL.
[endif]You
can then rename your DLL to MyFirstDLL (or anything you want).
the project window. Next, in the
properties window, change the Name property to MyFirstDLL.
[endif]Now,
once your done making your DLL, your going to have to save it as an actual
file. Goto File
mso-hansi-font-family:"Times New
Roman";mso-char-type:symbol;mso-symbol-font-family:
Wingdings'>
Make MyFirstDLL.dll… Save it
wherever you want. Just take note of
where you put it.
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Now that I’ve made my DLL, how do I use it?
You can call the DLL a
number of ways. In this tutorial, I
will only show you one.
Once you have a DLL file,
and want to make use of it, do the following.
[endif]Start
Microsoft Visual Basic.
[endif]Start
a Standard EXE. This will be the new
project that will use the DLL.
[endif]
mso-hansi-font-family:"Times New
Roman";mso-char-type:symbol;mso-symbol-font-family:
Wingdings'>
References. It will take some time
to load. This is a list of DLL files
that the application is currently using.
Click on browse and load the DLL that you just made.
functions, and properties into memory.
[endif]Now
is the time to use the DLL and see how the class works within the DLL.
Command1 and the other named Command2.
Next, make a textbox and name it Text1 .
[endif]
following code:
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[if
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mso-padding-alt:0cm 5.4pt 0cm 5.4pt'>
New";color:green'>'=====================================
made.
New";color:green'>'=====================================
!supportEmptyParas] [endif]
!supportEmptyParas] [endif]
!supportEmptyParas] [endif]
in the
make use of it.
color:black'>MyFirstDLL
New
color:green'>
color:green'>
!supportEmptyParas] [endif]
color:green'>
color:green'> 'Set text
'Set the property of MyFirstDLL to text1 text
'This shows how to set a property of the class/DLL.
color:green'>
New";color:green'>
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color:green'>
color:green'>
'Call the sub DisplayMsg in the DLL.
'This shows how to call a sub/function of the
class/DLL.
color:green'>
New";color:green'>
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color:green'>
'Initialize the Objects
"MyFirstDLL"
Text1.Text = "Enter text to be displayed
here..."
Command1.Caption = "Set Text"
Command2.Caption = "Display Text"
color:green'>
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[endif]Now
run the program and play around with it.
As you can see, when you click Set Text, it sets the property “Text” in
MyFirstDLL to whatever you typed in. When
you click Display Text, it calls the sub DisplayMsg in the DLL.
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Quick Things To Remember
[endif]To make a DLL, use ActiveX DLL project.
[endif]Project
"Times New Roman";mso-hansi-font-family:"Times New Roman";mso-char-type:symbol;
mso-symbol-font-family:Wingdings'>
Wingdings'>à References
[endif]Keep your DLLs in the same directory as the project.
[endif]Name everything to keep organization.
[endif]Make sure to use as many variables as possible in every
sub/function in your DLLs to allow diversity of programs.
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Conclusion
That concludes this tutorial!
program. Thank you for reading MyFirstDLL
and I hope you have learned the DLL-VB concept.
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