Concatenation operators join multiple strings into a single string. There are two concatenation operators, + and &; both carry out the basic concatenation operation, as shown below:
Dim x As String x = "Con" & "caten" & "ation" ' x equals "Concatenation". x = "Con" + "caten" + "ation" ' x equals "Concatenation".
These operators can also concatenate String variables, as in the following example:
Dim x As String = "abc" Dim y As String = "def" Dim z As String z = x & y ' z equals "abcdef". z = x + y ' z equals "abcdef".
If Option Strict is On, the + operator explicitly requires strings for concatenation operations. It also carries out arithmetic operations with numeric operands when Option Strict is On. If Option Strict is Off, however, the + operator supports a wide variety of implicit conversions for concatenation operations. For further information on these conversions, see + Operator.
The & operator is defined only for String operands, and it always widens its operands to String, regardless of the setting of Option Strict. The & operator is recommended for string concatenation because it is defined exclusively for strings and reduces your chances of generating an unintended conversion.