Ampersand vs plus for concatenating strings in VB.

Question

This question already has an answer here:

• String manipulation with & or + in VB.NET 6 answers

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.

Answer 1

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.

Answer 2

Micorosoft's preference is for VB progammers to use & for strings, NOT +.

You can also use the + operator to concatenate strings. However, to eliminate ambiguity, you should use the & operator instead.

Answer 3

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...).

Answer 4

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.

Answer 5

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