Why does the name of a source file affect compilation?

Question

I came across something really weird when I wrote a little lotto program in C++ called \"lotto.cpp\". Everything was fine until I wrote the write-to-file for my program. Whe

Answer 1

Error number 21 (on MacOS X 10.7.2) is EISDIR: Is a directory.

The name lotto seems to be a directory, not a file.