Recipe 8.11. Comparing Files or Folders

Problem

You want to compare the contents of two files or two folders to determine the differences.

Solution

Using a graphical user interface

Open the WinDiff application (windiff.exe) from the Resource Kit.
To compare two files, select File Compare Files from the menu. To compare two directories, select File Compare Directories.

Using a command-line interface

The fc.exe command compares two or more files:

> fc <File1Path> <File2Path>

Here is an example:

> fc c:\netdiag.log c:\old\netdiag.log

To compare two binary files include the /b option in the previous command.

Using VBScript

' This code compares the contents of two text-based files. ' ------ SCRIPT CONFIGURATION ------ strFile1 = "<FilePath1>"  ' e.g. c:\scripts\test1.vbs strFile2 = "<FilePath2>"  ' e.g. c:\scripts\test2.vbs ' ------ END CONFIGURATION --------- set objFSO = CreateObject("Scripting.FilesystemObject") set objFile1 = objFSO.opentextfile(strFile1,1) set objFile2 = objFSO.opentextfile(strFile2,1) arrFile1 = split(objFile1.ReadAll,vbNewLine) arrFile2 = split(objFile2.ReadAll,vbNewLine) objFile1.close objFile2.close if ubound(arrFile1) < ubound(arrFile2) then    intLineCount = ubound(arrFile1)    strError = strFile2 & " is bigger than " & strFile1 elseif ubound(arrFile1) > ubound(arrFile2) then    intLineCount = ubound(arrFile2)    strError = strFile2 & " is bigger than " & strFile1 else     intLineCount = ubound(arrFile2) end if for i = 0 to intLineCount    if not arrFile1(i) = arrFile2(i) then        exit for    end if next if i < (intLineCount + 1) then    WScript.Echo "Line " & (i+1) & " not equal"    WScript.Echo strError elseif strError <> "" then    WScript.Echo strError else     WScript.Echo "Files are identical." end if

Discussion

Out of all of the methods we described, Windiff is by far the smartest in terms identifying when lines have been added to a file or a section of text has been moved around. By comparison, the VBScript isn't nearly as robust. It simply checks line by line to determine if two text files are identical.