What is the difference between VBScript's + and & operator?

Question

On every site that talks about VBScript, the '&' operator is listed as the string concatenation operator. However, in some code that I have recently inherited, I see the '+' operator being used and I am not seeing any errors as a result of this. Is this an accepted alternative?

Answer 1

+ operator might backfire when strings can be interpreted as numbers. If you don't want nasty surprises use & to concatenate strings.

Answer 2

The + operator is overloaded, whereas the & operator is not. The & operator only does string concatenation. In some circles the & operator is used as a best practice because it is unambiguous, and therefore cannot have any unintended effects as a result of the overloading.

Answer 3

The & operator does string concatenation, that is, forces operands to be converted to strings (like calling CStr on them first). +, in its turn, forces addition if one of the expressions is numeric. For example:

1 & 2

gives you 12, whereas

1 + 2
"1" + 2
1 + "2"

give you 3.

So, it is recommended to use & for string concatenation since it eliminates ambiguity.