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 (Beginer Question #3) Passing a value to a function
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 Oct 23 2007, 11:38 AM
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#1
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UtterAccess Addict Posts: 241 From: DE and PA  |
I like to try and call functions where i can for individual processes. OOP?
How can i pass a value from where the function is being called to the actual function ie Sub call fn myvalue= .value end sub function use.value in code |
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Oct 23 2007, 11:43 AM
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#2
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UtterAccess VIP Posts: 4,621 From: North Carolina, USA |
An example function to add two numbers together;
Function AddNums(intNum1 as Integer, intNum2 as Integer) AddNums = intNum1 + intNum2) End Function Notice the arguments for the function in the first line. Then to call this function, it would be AddNums(1,2) The result would be 3. You wouldn't have to directly enter numbers, it also could be a variable or a form reference. |
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Oct 23 2007, 11:49 AM
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#3
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UA Editor + Utterly Certified Posts: 22,722 From: Melton Mowbray,Leicestershire (U.K) |
Hi
Matt missed of a "(" from the function.. CODE Function AddNums(intNum1 as Integer, intNum2 as Integer) AddNums = [color="red"]([/color]intNum1 + intNum2) End Function HTH's (IMG:http://www.utteraccess.com/forum/style_emoticons/default/thumbup.gif) |
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Oct 23 2007, 11:50 AM
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#4
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UtterAccess Addict Posts: 241 From: DE and PA |
hmm maybe i am using the wrong terminology.
so there are public and private subs as well as public and private functions. or at least that is what my book tells me. i want to pass a variable from a sub to a function? or do i have to declare the variable again in the function and look up the value i want again from a form? |
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Oct 23 2007, 11:55 AM
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#5
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UtterAccess VIP Posts: 4,621 From: North Carolina, USA |
You could declare a global variable - then you could set it and retrieve the value from anywhere. Usually in functions, the variables that are passed are arguments to the function (as shown above).
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Oct 23 2007, 12:03 PM
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#6
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UtterAccess Addict Posts: 241 From: DE and PA |
ahh i see. sorry had to look up global variable.
I would place this at the top Option Compare Database Public myvariable As String Option Explicit In a sub i would first set "myvalue" = nothing then give it a value and call the function Then in the Function i would use it by simply using myvalue in my code is that correct? |
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Oct 23 2007, 12:05 PM
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#7
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UtterAccess VIP Posts: 4,621 From: North Carolina, USA |
It depends on the function, but yes...
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Oct 23 2007, 12:08 PM
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#8
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UtterAccess Addict Posts: 241 From: DE and PA |
am i missing something? when should i be using a sub versus a function?
I am reading your response as if i am just not getting it. |
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Oct 23 2007, 12:42 PM
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#9
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UtterAccess Addict Posts: 201 |
Hi Antonio,
1) The general difference between a procedure (Sub) and a function (Function) is that a function is conventionally supposed to return a value, where a procedure cannot return a value. 2) As to passing and updating variables from within a function or procedure, it depends on how you pass them. By default, variables passed as arguments to functions can be modified (e.g. they are passed by reference). CODE [color="green"]' A Procedure To Increment A Value Passed As An Argument[/color] Public Sub MyIncrementProc(Value As Integer) Value = Value + 1 End Sub [color="green"]' A Function To Increment A Value Passed As An Argument[/color] Public Function MyIncrementFunc(Value As Integer) As Boolean On Error Goto Err_MyIncrementFunc Value = Value + 1 MyIncrementFunc = True Exit_MyIncrementFunc: Exit Function Err_MyIncrementFunc: MsgBox "MyIncrmementFunc ERROR" & Err.Description Resume Exit_MyIncrementFunc End Function [color="green"]' A Function To Increment A Value Passed As An Argument (By Value)[/color] Public Function MyOtherIncrementFunc(ByVal Value As Integer) As Integer On Error Goto Err_MyOtherIncrementFunc MyOtherIncrementFunc = Value + 1 Value = Value + 100 '<--this won't do anything to callers variable Value because it is passed in ByVal not ByRef (default) Exit_MyOtherIncrementFunc: Exit Function Err_MyOtherIncrementFunc: MsgBox "MyOtherIncrmementFunc ERROR" & Err.Description Resume Exit_MyIncrementFunc End Function Public Sub Test() Dim iValue As Integer Dim iTemp As Integer iValue = 1 Debug.Print "iValue=[" & iValue & "]" Call MyIncrementProc(iValue) Debug.Print "iValue (after increment procedure)=[" & iValue & "]" If MyIncrementFunc(iValue) Then Debug.Print "iValue (after increment function)=[" & iValue & "]" End If iTemp = MyOtherIncrementFunc(iValue) Debug.Print "iValue (after other increment function)=[" & iValue & "]" Debug.Print "iTemp (after other increment function)=[" & iTemp & "]" [/color] End Sub Hope this is useful, Jason |
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Oct 23 2007, 12:43 PM
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#10
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UtterAccess VIP Posts: 4,621 From: North Carolina, USA |
The general difference between sub and functions is that functions produce a value. Subs merely process lines of code.
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Oct 23 2007, 01:03 PM
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#11
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UtterAccess Addict Posts: 241 From: DE and PA |
Oh wow okay I really get it now.
I should probably rename my functions as subs then because they do not produce a value. Thank you Matt and Jason! Jason- after your procedure name you fill things in the ( ) what is that called? the are in between the brackets Public Function MyOtherIncrementFunc(ByVal Value As Integer) As Integer i want to look it up. up until now i havent used it myself |
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Oct 23 2007, 01:14 PM
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#12
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UtterAccess Addict Posts: 201 |
Hi Antonio,
The items within the parenthesis of a Function or Procedure are called arguments (sometimes they are also called parameters). In the Office Online help you can search on 'About procedures' and find the reference on syntax. Hope this helps, Jason |
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