Question

I am wondering what is the ‘best practice’ to break long strings in C# source code. Is this string

'string1'+ 'string2'+ 'string3' 

concatenated during compiling or in run time?

Answer 1

It’s done at compile time. That’s exactly equivalent to ‘string1string2string3’.

Suppose you have:

string x = 'string1string2string3' string y = 'string1' + 'string2' + 'string3' 

The compiler will perform appropriate interning such that x and y refer to the same objects.

EDIT: There’s a lot of talk about StringBuilder in the answers and comments. Many developers seem to believe that string concatenation should always be done with StringBuilder. That’s an overgeneralisation – it’s worth understanding why StringBuilder is good in some situations, and not in others.