Why a full stop, “.” and not a plus symbol, “+”, for string concatenation in PHP?

Question

Why did the designers of PHP decide to use a full stop / period / \".\" as the string concatenation operator rather than the more usual plus symbol \"+\" ?

Is there

Answer 1

+ should always be defined as a commutative operation (i.e., A+B = B+A). In the case of string concatenation, this is not the case ("foo" + "bar" != "bar" + "foo"). As such, + is not a good operator to use for the concatenation operation. Whether or not the language authors had this in mind when they used . instead (which is close to the multiplication operator, for which commutativity need not hold) remains to be seen, but it was a good decision nonetheless.