Question

Help me settle an argument here.

Is this:

SqlCommand cmd = new SqlCommand( 'sql cmd', conn); 

treated exactly the same as this:

const string s = 'sql cmd'; SqlCommand cmd = new SqlCommand( s, conn); 

Ie. does it make a difference if I state specifically that the string s is a const.

And, if it is not treated in the same way, why not?

Answer 1

In the latter snippet, it’s not that the string is const – it’s that the variable is const. This is not quite the same as const in C++. (Strings are always immutable in .NET.)

And yes, the two snippets do the same thing. The only difference is that in the first form you’ll have a metadata entry for s as well, and if the variable is declared at the type level (instead of being a local variable) then other methods could use it too. Of course, due to string interning if you use ‘sql cmd’ elsewhere you’ll still only have a single string object in memory… but if you look at the type with reflection you’ll find the const as a field in the metadata with the second snippet if it’s declared as a constant field, and if it’s just a local variable it’ll be in the PDB file if you build one.