FC--Notes

Reporting differences between files for an ASCII comparison

When you use FC for an ASCII comparison, MS-DOS reports differences between
two files by displaying the name of the first file, followed by the last
line to match in both files, followed by the lines from filename1 that
differ between the files, followed by the first line to match in both files.
MS-DOS then displays the name of the second file, followed by the last line
to match, followed by the lines from filename 2 that differ, followed by the
next line to match.

Using the /B switch for binary comparisons

MS-DOS uses the following format to report mismatches found during a binary
comparison:

    xxxxxxxx: yy zz

The value of xxxxxxxx specifies the relative hexadecimal address for the
pair of bytes, measured from the beginning of the file. Addresses start at
00000000; the hexadecimal values for yy and zz represent the mismatched
bytes from filename1 and filename2, respectively.

Using wildcards

You can use wildcards (* and ?) in either of the filenames you specify with
the FC command. If you use a wildcard in filename1, FC compares all the
specified files to the file specified by filename2. If you use a wildcard in
filename2, FC uses the corresponding value from filename1.

How FC uses memory

When comparing ASCII files, FC uses an internal buffer (large enough to hold
100 lines) as storage. If the files are larger than the buffer, FC compares
what it can load into the buffer. If FC does not find a match in the loaded
portions of the files, it stops and displays the following message:

    Resynch failed. Files are too different.

When comparing binary files that are larger than available memory, FC
compares both files completely, overlaying the portions in memory with the
next portions from the disk. The output is the same as that for files that
fit completely in memory.