问题
What is the difference between:
string1 + string2
and
string1 & string2
Are they equivalent? Why have two different symbols that do the same thing?
回答1:
The expressions are the same as long as the operands are strings; if not, + might add them instead depending on type conversions. & guarantees you won't get anything except a string concatenation, and will convert operands to strings if possible to do so.
There's an MSDN entry about Concatenation operations in Visual Basic that explains it:
The & Operator (Visual Basic) 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.
回答2:
The two expressions are equivalent, but the operators are not. + can be used as an arithmetic operator as well as for string concatenation, & can only be used for the latter.
来源：https://stackoverflow.com/questions/3365197/vba-difference-between-and