# SRCCOM

> [HTML Version](srccom_lit.htm)

_Updated March 2025; see History_

**SRCCOM \{listfile=\} oldfile, newfile \{switches\}**

SRCCOM compares two source files, reporting the differences. This is useful, for example, when comparing two versions of a program to see what has changed between them. It is most useful when the differences between the files are few; when they are substantial, it becomes both overwhelmed and overwhelming.  

| **Switch** | **Effect ** |
|------|------|
| /B | Brief listing: same as /Q but without line numbers |
| /Q | Quick listing: list only the lines that differ between the two files |
| /S | Silent: ignores blank lines and whitespace differences |
| /? | Writes switch listing and usage info to the screen |




Under Unix, there is a much more powerful file comparison utility call _diff_, and in some cases, _diff3_, which can compare three files at a time. See the notes on [DIFF](diff_lit.md), an A-Shell front-end to _diff_.

Note also that SRCCOM.LIT includes the list file name and switches in the listing header, matching the format of the AMOS version.

**History**

2025 March, A-Shell 7.0.1774, SRCCOM.LIT 2.0(205):  optimization improvements, both in terms of performance and minimizing the amount of difference reported. Also, add lifesigns.

2021 December, A-Shell 6.5.1709, SRCCOM.LIT 2.0(201):  routine rewritten to implement various improvements/fixes:

•	No longer requires a memory partition of 1MB or more.

•	Supports a new switch /S which ignores whitespace differences.

•	Removed limit on line length, which previously was 512 characters.

•	Supports inserted blocks of up to 10000 lines, up from 750.

•	Reduces tendency for single-line "premature matches". For example, when a block of new code is inserted, SRCCOM previously would re-sync on a single line match (even a blank line) between the original code and the new code, causing the inserted block to appear like a fragmented series of multiple insertions instead of a single block.

•	Is now able to recognize "parallel differences" of up to 100 lines. These result from line changes rather than insertions/deletions.

•	The /Q mode now outputs the matching pair both before and after a set of differences.