In VB.NET, is there any advantage to using &
to concatenate strings instead of +
?
For example
Dim x as String = "hello" + " there"
vs.
Dim x as String = "hello" & " there"
Yes, I know for a lot of string concatenations I'd want to use StringBuilder
, but this is more of a general question.
Microsoft's preference is for VB programmers to use &
for strings and not +
.
You can also use the + operator to concatenate strings. However, to eliminate ambiguity, you should use the & operator instead.
I've heard good, strong arguments in favor of both operators. Which argument wins the day depends largely on your situation. The one thing I can say is that you should standardize on one or the other. Code that mixes the two is asking for confusion later.
The two arguments I remember right now for favoring &
:
- If you're not using
Option Strict
and have two numeric strings, it's easy for the compiler to confuse your meaning of of the+
operator with, you know, arithmetic addition - If you're updating a lot of older vb6-era code it helps not to have to convert the concatenation operators ( and remember: we want consistency).
And for +
:
- If you have a mixed vb/C# shop, it's nice to only have one concatenation operator. It makes it easier to move code between languages and means just that much less of a context switch for programmers when moving back and forth between languages
&
is almost unique to VB, while+
between strings is understood in many languages to mean concatenation, so you gain a little something in readability.
I prefer using &
for string concatenations in VB.NET
One reason for this is to avoid any confusion e.g
MessageBox.Show(1 & 2) ' "12"
MessageBox.Show(1 + 2) ' 3
It's safer to use & since you're making your intention clear to the compiler (I want to concatenate these two values and they should both be converted to strings).
Using + can lead to hard to find bugs if the strings are numerical values, at least if the option strict is off.
For example:
1 + "1" = 2 ' this fails if option strict is on
1 & "1" = 11
Edit: though if you're concatenating a non-string you should probably use some better method anyway.
I suppose it is historical (non .NET Visual Basic uses &, not sure why they introduced the +) and a matter of taste (I prefer & because we concatenate strings, we don't add them...).
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