Programming Forums > Application Development > Visual Basic .NET

randum77 · Apr 11th, 2007, 3:22 PM

I've not been around in a while, but i've not had time to work on programming in a couple months. Anyhow, i'm wondering how i would go about passing variables between forms. I want to use them to control what appears on another form, rather then reformation one form everytime a button is clicked.

I searched through the MSDN and I've come up dry. Do i need to store the variable in a function or something of that sort? Thanks in advance.

_marshall_

randum77 · Apr 11th, 2007, 3:37 PM

Excuse me, I meant to say class. Do I need to store the variable I want available in all the forms in a class of some sort?

melbolt · Apr 12th, 2007, 9:47 AM

Hi Marshall (btw, that's my first name as well)

There are a couple of ways you can go about exchanging the data between forms(or rather classes).

The first way, which it appears you know about already, is by instantiating or creating one form from within the other so you have a reference to this class in which you can access its public variables or properties. What I mean by this is you dim the new form within the initial form, this new form contains public variables or properties which you can then get at using classinstancename.variablename

I assume you already know about this way from reading your first post but it sounds like you want to have the ability to update the 2nd form automatically each time the data on the initial form changes?

If it were me, here is the approach I would take. you can use events to pass the data between forms automatically when something happens. so, for example, if the user clicks the save button on form1, the data in the textbox on form1 can automatically be sent to form2 when this happens using this technique.

So what you need to do is raise the event on the first form and catch it on the second form and in the event handler on the second form you can go get the data from the property or public variable.

alternatively you could put the data in the event args being sent with the event.

here is a look at an example I found online:
http://www.devcity.net/Articles/102/multipleforms3.aspx

If you have questions about what is going on here, feel free to post again.

good luck.

randum77 · Apr 12th, 2007, 2:44 PM

Melbot, I appreciate the reply. I'll take some time to understand what's going on so I can ask some questions if I get confused. The example link looks like it will do what I want, I just may modify it. I've been looking at some of the code i wrote a couple months back and it's coming back to me.

_marshall_ (a great name!)

randum77 · Apr 16th, 2007, 2:55 PM

Ok, I understand what's going w/ the previous link. It's working more on the theory of having Frm1 and Frm2. When you type in Frm2 it updates the info in labels on Frm1. What I am doing is when you hit a button on Frm1, it opens Frm2 w some variable from Frm dictating how Frm2 should look.

What I've done is push the variable into the class i have built. I then try and access that class on Frm2 when it loads to decide how the screen should look. And it's not working. I'm sure it's something simple. I probably have 2 different instances of the class alive with 2 different sets of variables.

Based on the link you gave me, I should be able to figure it out, so I am going to blow some time working on that. In the mean time, any info?

_marshall_

randum77 · Apr 16th, 2007, 3:44 PM

Ok, I got it all working the way I wanted. I appreciate the help Melbolt. I just setup all the event sequences in Frm1 and forced the changes to Frm2 from Frm1 based on variables.

melbolt · Apr 16th, 2007, 5:42 PM

congrats

randum77 · Apr 17th, 2007, 10:38 AM

Interesting side note. I found that if I put the following at the top of FrmMain, then FrmLocate is available from FrmMain.

(Toggle Plain Text)

Dim WithEvents Locate As New frmLocate()

Then when I want to modify a variable or property from FrmLocate, i can just use the following.

(Toggle Plain Text)

 Locate.lblType2.Text = "Manufacturing"

I"ll be posting later about another section of this application I have to work through. I'm sure it'll be confusing the hell out of me.

Apr 11th, 2007, 3:22 PM	#1
randum77 Programmer Join Date: Jun 2006 Location: Fayettehell, NC Posts: 56 Rep Power: 3	Passing variable from one form to another I've not been around in a while, but i've not had time to work on programming in a couple months. Anyhow, i'm wondering how i would go about passing variables between forms. I want to use them to control what appears on another form, rather then reformation one form everytime a button is clicked. I searched through the MSDN and I've come up dry. Do i need to store the variable in a function or something of that sort? Thanks in advance. _marshall_ __________________ _Marshall_ "America has bred a society that is innocent and incapable of accepting responsibility, but yet, is able to place blame on others without guilt."

Apr 11th, 2007, 3:37 PM	#2
randum77 Programmer Join Date: Jun 2006 Location: Fayettehell, NC Posts: 56 Rep Power: 3	Excuse me, I meant to say class. Do I need to store the variable I want available in all the forms in a class of some sort? __________________ _Marshall_ "America has bred a society that is innocent and incapable of accepting responsibility, but yet, is able to place blame on others without guilt."

Apr 12th, 2007, 9:47 AM	#3
melbolt Hobbyist Programmer Join Date: Feb 2005 Location: PA, USA Posts: 233 Rep Power: 4	Hi Marshall (btw, that's my first name as well) There are a couple of ways you can go about exchanging the data between forms(or rather classes). The first way, which it appears you know about already, is by instantiating or creating one form from within the other so you have a reference to this class in which you can access its public variables or properties. What I mean by this is you dim the new form within the initial form, this new form contains public variables or properties which you can then get at using classinstancename.variablename I assume you already know about this way from reading your first post but it sounds like you want to have the ability to update the 2nd form automatically each time the data on the initial form changes? If it were me, here is the approach I would take. you can use events to pass the data between forms automatically when something happens. so, for example, if the user clicks the save button on form1, the data in the textbox on form1 can automatically be sent to form2 when this happens using this technique. So what you need to do is raise the event on the first form and catch it on the second form and in the event handler on the second form you can go get the data from the property or public variable. alternatively you could put the data in the event args being sent with the event. here is a look at an example I found online: http://www.devcity.net/Articles/102/multipleforms3.aspx If you have questions about what is going on here, feel free to post again. good luck. __________________ I have never let my schooling interfere with my education. -Mark Twain- Xbox live gamertag: melbolt

Apr 12th, 2007, 2:44 PM	#4
randum77 Programmer Join Date: Jun 2006 Location: Fayettehell, NC Posts: 56 Rep Power: 3	Melbot, I appreciate the reply. I'll take some time to understand what's going on so I can ask some questions if I get confused. The example link looks like it will do what I want, I just may modify it. I've been looking at some of the code i wrote a couple months back and it's coming back to me. _marshall_ (a great name!) __________________ _Marshall_ "America has bred a society that is innocent and incapable of accepting responsibility, but yet, is able to place blame on others without guilt."

Apr 16th, 2007, 2:55 PM	#5
randum77 Programmer Join Date: Jun 2006 Location: Fayettehell, NC Posts: 56 Rep Power: 3	More questions Ok, I understand what's going w/ the previous link. It's working more on the theory of having Frm1 and Frm2. When you type in Frm2 it updates the info in labels on Frm1. What I am doing is when you hit a button on Frm1, it opens Frm2 w some variable from Frm dictating how Frm2 should look. What I've done is push the variable into the class i have built. I then try and access that class on Frm2 when it loads to decide how the screen should look. And it's not working. I'm sure it's something simple. I probably have 2 different instances of the class alive with 2 different sets of variables. Based on the link you gave me, I should be able to figure it out, so I am going to blow some time working on that. In the mean time, any info? _marshall_ __________________ _Marshall_ "America has bred a society that is innocent and incapable of accepting responsibility, but yet, is able to place blame on others without guilt."

Apr 16th, 2007, 3:44 PM	#6
randum77 Programmer Join Date: Jun 2006 Location: Fayettehell, NC Posts: 56 Rep Power: 3	Ok, I got it all working the way I wanted. I appreciate the help Melbolt. I just setup all the event sequences in Frm1 and forced the changes to Frm2 from Frm1 based on variables. __________________ _Marshall_ "America has bred a society that is innocent and incapable of accepting responsibility, but yet, is able to place blame on others without guilt."

Apr 16th, 2007, 5:42 PM	#7
melbolt Hobbyist Programmer Join Date: Feb 2005 Location: PA, USA Posts: 233 Rep Power: 4	congrats __________________ I have never let my schooling interfere with my education. -Mark Twain- Xbox live gamertag: melbolt

Apr 17th, 2007, 10:38 AM	#8
randum77 Programmer Join Date: Jun 2006 Location: Fayettehell, NC Posts: 56 Rep Power: 3	Interesting side note. I found that if I put the following at the top of FrmMain, then FrmLocate is available from FrmMain. (Toggle Plain Text) Dim WithEvents Locate As New frmLocate() Dim WithEvents Locate As New frmLocate() Then when I want to modify a variable or property from FrmLocate, i can just use the following. (Toggle Plain Text) Locate.lblType2.Text = "Manufacturing" Locate.lblType2.Text = "Manufacturing" I"ll be posting later about another section of this application I have to work through. I'm sure it'll be confusing the hell out of me. __________________ _Marshall_ "America has bred a society that is innocent and incapable of accepting responsibility, but yet, is able to place blame on others without guilt."

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Programming Forums > Application Development > Visual Basic .NET

Passing variable from one form to another