Morale of a story: ~ is the right choice for concat operator

[rumbu]

On Saturday, 26 May 2018 at 10:08:35 UTC, Dukc wrote:
> On Saturday, 26 May 2018 at 09:01:29 UTC, rumbu wrote:
>> Sorry, but the mistake here is the fact that you wrongly 
>> assume C behavior in C#.
>
> Yes it is. But that does not make differentiating concat and 
> addition in language desing any less worthwhile. In car 
> crashes, the mistake is usually made by a driver, but I know 
> no-one who says safety belts aren't worthwhile.
>
>> Adding chars to an existing string will result in a string as 
>> in the language specification.
>
> In fact I didn't make the mistake there. What surprised me was 
> that adding two INDIVIDUAL chars result in a string. When op+ 
> is srictly for mathematical summing, there are no ambiquites.

Adding 2 individual chars in C# (and in D also) will result in an 
int. Adding an int to a string will box the int and ToString() 
will be called on the resulted object => result is a string. So 
'a' + 'b' + "sssss" = 195 + "sssss" = 195.ToString() + "sssss" = 
"195sssss".

Therefore your first example will work correctly if you convert 
the int result back to char: (char)('a' + 'b') + "sssss" will 
render the correct result.

Even if C# would use '~' instead of '+', you had a type 
conversion problem, not an operator problem, you wrongly assumed 
that adding two chars will result in a char, not an int. In the 
hypothetically code 'a' + 'b' ~ "sssss" is also "195sssss".