unsigned long fwrite (buffer, count, size, outputid)
void *buffer;
unsigned count;
unsigned size;
int outputid;

where:

This macro writes the contents of a buffer to a file or window. You must define the identity of the file with either the fopen macro or the FOPEN command.

If you are writing to a file, it must be opened in write mode, for example: fopen(100,"c:\\myfiles\\data_out.txt","w").

The example on Example also shows you how to use fwrite in a macro.