As Al said, there is no error raised by STRTOFILE, but you can use it's return value (the number of bytes written), which in the case you showed should return 0
"The five senses obstruct or deform the apprehension of reality."
Jorge L. Borges?
"Premature optimization is the root of all evil in programming."
Donald Knuth, repeating C. A. R. Hoare
"To die for a religion is easier than to live it absolutely"
Jorge L. Borges