C# Why does '+' + a short convert to 44

I have a line of code that looks like this:

MyObject.PhoneNumber = '+' + ThePhonePrefix + TheBizNumber;

Basically, I'm creating a phone number in E164 format and then I assign that string to a string property of an object. ThePhonePrefix is a short that holds the international phone prefix and TheBizNumber is a string that holds the phone number digits.

Why didn't the compiler bug when I was concatenating a short in the string in the first place? And then why does '+' + 1 equal 44?? This was a pretty hard bug to track because there was no compile error and 44 is the phone prefix for the UK so everything "looked" like it was working because the client-side code just saw a UK number. Why 44?

Thanks.

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Answer:

Why didn't the compiler bug when I was concatenating a short in the string in the first place?

String concatenation using + sign internally calls string.Concat, which internally calls ToStringon each parameter. Hence no error.

why does '+' + 1

You are doing character/numeric arithmetic. 43 being value of + and short/int 1 is 44.

Because of operator + associativity from left to right it is first character/numeric addition and then string concatenation.

So it is like:

MyObject.PhoneNumber = ('+' + ThePhonePrefix) + TheBizNumber;

You can use "+" to mark it as a string or explicitly call String.Concat like:

var result = string.Concat('+', ThePhonePrefix, TheBizNumber);
website:http://stackoverflow.com/questions/29397495/why-does-a-short-convert-to-44
posted @ 2015-04-07 09:27  vigorpush  阅读(110)  评论(0)  编辑  收藏  举报