[JimWright949]

fopen opens a file for writing (in your case). You will only need to perform this once. To write a string into a file I would use fprintf(data,"Hello world");.
At the end of your program use a fclose(data); to close the file and flush the buffers out.

In other words you need a fclose(data); command for every fopen command you have. An nether fopen nor fclose is writting any data to a file.

-Jim