Perl is an old but notable exception. + is purely for addition in the base language.
If you try to add two strings with it, they’ll be converted to numbers based on any number-like characters they have at their left hand ends, and, if warnings are enabled (and you should definitely do that), you’ll get runtime warnings about it if there’s even anything vaguely non-numeric about them.
e.g. “1”+“11” will get you 12 with no complaint, warnings or otherwise. Not even the string “12” either, although it’s hard to determine one from the other in Perl. It’s a need-to-know kind of thing. And you generally don’t.
“a”+“bb” gives 0 as the result because they’re not numbers and “1a”+“11bb” will give 12, but these latter two will give warnings. Two each, in fact, one for each dodgy parameter.
String concatenation is done with the dot operator instead. “1”.“11” gives “111”. This comes with it’s own minor problems, but at least + is safe.
It’s an issue with most if not all languages that aren’t strongly typed.
Perl is an old but notable exception. + is purely for addition in the base language.
If you try to add two strings with it, they’ll be converted to numbers based on any number-like characters they have at their left hand ends, and, if warnings are enabled (and you should definitely do that), you’ll get runtime warnings about it if there’s even anything vaguely non-numeric about them.
e.g. “1”+“11” will get you 12 with no complaint, warnings or otherwise. Not even the string “12” either, although it’s hard to determine one from the other in Perl. It’s a need-to-know kind of thing. And you generally don’t.
“a”+“bb” gives 0 as the result because they’re not numbers and “1a”+“11bb” will give 12, but these latter two will give warnings. Two each, in fact, one for each dodgy parameter.
String concatenation is done with the dot operator instead. “1”.“11” gives “111”. This comes with it’s own minor problems, but at least + is safe.