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Question

vb.net string concatenation string + function output + string = string + function output and no more

Answer 1

+1 A:

Consider the following code that should be the equivalent of your code:

Dim someString As String = String.Empty

someString = someString + "<G3Grid:Spots>" + "SomeValue" + "</G3Grid:Spots>"

Console.WriteLine(someString)

someString = String.Empty
someString = someString + "<G3Grid:Spots>" + "SomeValue"
someString = someString + "</G3Grid:Spots>"

Console.WriteLine(someString)

I tested it and in both cases the output is: <G3Grid:Spots>SomeValue</G3Grid:Spots>

If you don't get the same results then it's because either m_rFlight.Layout is not a string, or Me.gvwSpots.LayoutToString() doesn't return a string and does something strange with the + operator. You can use the & operator instead to make sure that only string concatenation is performed.

Meta-Knight 2010-02-04 16:02:32

xpda 2010-02-06 16:32:24

Answer 2

A:

As Meta-Knight said, except that I would recommend using the StringBuilder class:

Dim myString As New System.Text.StringBuilder

myString .Append("<G3Grid:Spots>")
myStrinAppend(Me.gvwSpots.LayoutToString())
myString.append("</G3Grid:Spots>")

m_rFlight.Layout = myString.ToString()

Joel Etherton 2010-02-04 16:08:30

So I ask why the code is doing something and you suggest using a stringbuilder?The code gets executed once for every user, using the stringbuilder for performance benefits won't be that usefull.The final string is no larger then a couple of 1000 characters.

Barfieldmv 2010-02-08 17:07:45

@Barfieldmv: Yah, like I said, I agree with Meta-Knight. It looked to me like you're you having goofy append issues with your string possibly because of a typing problem. Using StringBuilder might help alleviate that by ensuring that the output is definitely a string. Other than that, you shouldn't be using + to concatenate (as other have said). I don't recommend StringBuilder for performance in this case. I recommend it for type safety.

Joel Etherton 2010-02-08 17:20:02

Answer 3

A:

You can use string.concat

m_rFlight.Layout = string.concat(m_rFlight.Layout, "<G3Grid:Spots>",_
  Me.gvwSpots.LayoutToString(), "</G3Grid:Spots>")

or, as Meta-Knight mentioned, & instead of +. (It will always convert to string before concatenation.)

m_rFlight.Layout &= "<G3Grid:Spots>" & Me.gvwSpots.LayoutToString() & "</G3Grid:Spots>"

xpda 2010-02-06 16:38:52

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vb.net string concatenation string + function output + string = string + function output and no more

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