I have this print statement.

printf("(n * o ) % m == 0 is invalid so exiting. \n");

And this is the output.

(n * o ) Success == 0 is invalid so exiting.

I don't even have the word "Success" anywhere in my program. I don't see anything in the printf documentation about it treating m special.

http://www.cplusplus.com/reference/cstdio/printf/

From the GNU C library:
The ‘%m’ conversion prints the string corresponding to the error code in errno.