لطفا منتظر باشید ...
8.22. Comparing the Contents of Two Files
8.22.1. Problem
You have two files and want to see
whether they''re the same or different.
8.22.2. Solution
Use the standard File::Compare module with filenames, typeglobs, or
any indirect filehandles:
use File::Compare;
if (compare($FILENAME_1, $FILENAME_2) = = 0) {
# they''re equal
}
if (compare(*FH1, *FH2) = = 0) {
# they''re equal
}
if (compare($fh1, $fh2) = = 0) {
# they''re equal
}
8.22.3. Discussion
The File::Compare module (standard as of v5.8 and available on CPAN
if you have an earlier version of Perl) compares two files for
equality. The compare function, exported by
default, returns 0 when the files are equal, 1 when they differ, and
-1 when any error occurs during
reading.
To compare more than two filehandles, simply loop, comparing two at a
time:
# ensure all filehandles in @fh hold the same data
foreach $fh (@fh[1..$#fh]) {
if (compare($fh[0], $fh)) {
# $fh differs
}
}
If you want details of exactly how two files differ, use the
Text::Diff module from CPAN:
use Text::Diff;
$diff = diff(*FH1, *FH2);
$diff = diff($FILENAME_1, $FILENAME_2, { STYLE => "Context" });
In addition to filehandles, diff can also take
filenames, strings, and even arrays of records. Pass a hash of
options as the third argument. The STYLE option
controls the type of output returned; it can be
"Unified" (the default),
"Context", or "OldStyle". You
can even write your own class for custom diff formats.
The value returned by diff is a string similar to
the output of the diff(1) program. This string
is in valid diff format, suitable for feeding into
patch(1). Although Text::Diff will not always
produce the same output as GNU diff, byte for
byte, its diffs are nevertheless correct.
8.22.4. See Also
The documentation for the standard File::Compare module; the
documentation for the CPAN module Text::Diff; the
diff(1) and patch(1)
manpages.
