scottrick: > Where is the function 'format' defined?
You need to add at the top of the module: import std.conv: format; Or: import std.conv; > Also, what is that 'unittest' block? It compiles fine as is, but if I refer > to format outside of > unittest, it will not compile. Also, if I compile and run your > example, it doesn't do anything, since main() is empty? It's an block of unit tests :-) Currently in your program they are not even compiled, so the format is not used. To run the unit tests you need to compile with -unittest compiler switch (with DMD). See also: http://www.digitalmars.com/d/2.0/unittest.html Bye, bearophile