Compare two files (or sets of files). Display items which do not match.

      COMP [pathname1] [pathname2] [/D] [/A] [/L] [/N=number] [/C]

   pathname1 The path and filename of the first file(s)
pathname2 The path and filename of the second file(s)
/D Display differences in decimal format. (default) /A Display differences in ASCII characters.
/L Display line numbers for differences. /N=number Compare only the first number of lines in the file. number can be between 1 and 2,147,483,647. /C Do a Case insensitive string comparison

Running COMP with no parameters will result in a prompt for the 2 files and any options

To compare sets of files, use wildcards in pathname1 and pathname2 parameters.

When used with the /A option COMP is similar to the FC command but it displays the individual characters that differ between the files rather than the whole line.

If the files contain a different number of characters, then by default, COMP will just report: 'Files are different sizes.'
To compare files of different sizes, use /N=number to compare only the first n lines (common portion of each file). If you provide a number greater than the number of lines in either file then COMP will compare every line.

If more than 10 mismatches are found COMP will end and display the partial results.
COMP will report if one file contains fewer lines than the other, this count is zero based, so 'File2 has only 4 lines' means there are 5 lines in the file.

COMP will normally finish with a Compare more files (Y/N) prompt,
to suppress this: ECHO n|COMP options


COMP will return an ErrorLevel as follows:

0 Files are identical
1 Files are different
2 Cannot open one of the files or invalid arguments or invalid switch


Compare file1.txt and file2.txt

COMP file1.txt file1.txt

“Shall I compare thee to a summer's day” ~ William Shakespeare

Related commands

FC - Compare two files and display any LINES which do not match.
Equivalent PowerShell: Compare-Object - Compare the properties of objects, e.g. compare content of files.
Equivalent bash command (Linux): cmp - Compare two files.

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