Visual Basic 2005 Numerical Functions Support

I'm working with VB 2005. I'm rather new to the visual basic department, i'm not much of a fan of it either.

Anyway, I have a very simple program. With 2 buttons, one labeled "btnCalculate" and one labeled "btnExit", and those titles are rather odvious as to what they do.

I have 3 categories:

Initial Quality:
<insert text field>(txtQuality)

Amount Sold
<insert text field>(txtSold)

Amount Purchased
<insert text filed here>(txtPurchased)

Current Quality:
<insert label label>(lblinStock)

What I want, is to calculate the current quanitity by subtracting the quantity sold from the inital quantity, and then adding the quantity purchased to the result. Then display it the current quantity in my lblInstock" control.

I want to use the functions:
CDbl
CInt
CSng
CStr

o.o But i'm unsure of how to use them, I've googled it but still don't know how to do it.

Any support would be much appreciated.

Thank You,

Red_X_

 

Dim origAmnt as Integer=Integer.Parse(txtQuantity.Text)
Dim soldAmnt as Integer=Integer.Parse(txtSold.Text)
Dim purchAmnt as Integer=Integer.Parse(txtPurchased.Text)

Dim currentQuantity as Double= (origAmnt-soldAmnt)+purchAmnt

lblInstock=currentQuantity.ToString()


The following
CDbl
Cint
CSng
CStr

are all deprecated functions from VB6. In other words. don't use them as it's goes against the way of doing things in .NET

 

Hmm. I was told it would making things easier to read. As they are simple functions.

But if I was to use those, how would they be used? If its not to much trouble.

 

don't use them, they are deprecated and anyone who tells you to use them doesn't understand .NET

BUT, you would use them like CDbl([value to convert]) or CStr([value to convert]) etc etc.

 

lblInstock.text=currentQuantity.ToString()

 

crap.. I always do that.

 

Remarks from the Microsoft help files under Type Conversion Functions

As a rule, you should use the Visual Basic type conversion functions (like CStr, CInt, etc.) in preference to the .NET Framework methods such as ToString(), either on the Convert class or on an individual type structure or class. The Visual Basic functions are designed for optimal interaction with Visual Basic code, and they also make your source code shorter and easier to read. In addition, the .NET Framework conversion methods do not always produce the same results as the Visual Basic functions, for example when converting Boolean to Integer.

 

They are legacy function names that are "shorthand" for ctype; Cstr essentially calls Ctype(). MS Docs also suggest that type names should not be included in function names, variable names etc. They broke their own rules with this because people didn't want to type Ctype(variable, object) or god forbid object.tostring(). While there are vb functions that do have some optimizations, these are not among them.

Casting a string to an int should be done
Dim i as integer=0
Dim x as string="*#"
Dim successOrFailure as Boolean=integer.TryParse(x, i)

using Cint(x) will result in an invalid cast. So much for validation and while you're worried about your code "looking" clean, it won't work and you're left wondering "WTF".

So I re-iterate. Use the .NET methods please and steer clear of the easy button.