// Open file for writing
if ( (fp=fopen(file_name, "w"))==NULL)
{
  printf("Can't open file_name\n");
  exit(1);
}

// Put single char in file
fputc( cc, fp );

// Read chars from a file, up to EOF
while (( cc = fgetc(fc)) != EOF )

// Read chars form a binary file, up to true-EOF
while ( !feof(fp) )
{
  cc = fgets(fc);
}
// fwrite - used to wirte binary data to a file pointer
fwrote(                // write to a file 
        &num,          // data starting address 
        sizeof(float), // chunck size to write
        1,             // number of chunks
        fp             // address of file to write to
) 
// fread - use to read binary data from a file pointer
fread(                 // read from a file
        &num,          // read to address of variable num
        sizeof(float), // chunck size to read 
        1,             // number of chunks
        fp             // address of file to read from
)