Posts Tagged ‘Productivity’

My Embedded Toolbox: Source Code Whitespace Cleanup

Monday, August 7th, 2017 Miro Samek

In this installment of my “Embedded Toolbox” series, I would like to share with you the free source code cleanup utility called QClean for cleaning whitespace in your source files, header files, makefiles, linker scripts, etc.

You probably wonder why you might need such a utility? In fact, the common thinking is that compilers (C, C++, etc.) ignore whitespace anyway, so why bother? But, as a professional software developer you should not ignore whitespace, because it can cause all sorts of problems, some of them illustrated in the figure below:


  1. Trailing whitespace after the last printable character in line can cause bugs. For example, trailing whitespace after the C/C++ macro-continuation character ‘\’ can confuse the C pre-processor and can result in a program error, as indicated by the bug icons.
  2. Similarly, inconsistent use of End-Of-Line (EOL) convention can cause bugs. For example, mixing the DOS EOL Convention (0x0D,0x0A) with Unix EOL Convention (0x0A) can confuse the C pre-processor and can result in a program error, as indicated by the bug icons.
  3. Varying amount of trailing whitespace at the end of the lines plus inconsistent use of tabs and spaces can cause unnecessary churn in the version control system (VCS) in source files that otherwise should be identical. Sure, many VCSs allow you to “ignore whitespace”, but are files differing in size by as much as 20% really identical?
  4. Inconsistent use of tabs and spaces can lead to different rendering of the source code by different editors and printers.

Note: The problems caused by whitespace in the source code are particularly insidious, because you don’t see the culprit. By using an automated whitespace cleanup utility you can save yourself hours of frustration and significantly improve your code quality.


 QClean Source Code Cleanup Utility

QClean is a simple and blazingly fast command-line utility to automatically clean whitespace in your source code. QClean is deployed as natively compiled executable and is located in the QTools Collection (in the sub-directory  qtools/bin ). QClean is also available in portable source code and can be adapted and re-compiled on all desktop platforms (Windows, POSIX –Linux, MacOS).

Using QClean

Typically, you invoke QClean from a command-line prompt without any parameters. In that case, QClean will cleanup white space in the current directory and recursively in all its sub-directories.

Note: If you have added the qtools/bin/ directory to your PATH environment variable (see Installing QTools), you can run qclean directly from your terminal window.


As you can see in the screen shot above, QClean processes the files and prints out the names of the cleaned up files. Also, you get information as to what has been cleaned, for example, “Trail-WS” means that trailing whitespace has been cleaned up. Other possibilities are: “CR” (cleaned up DOS/Windows (CR) end-of-lines), “LF” (cleaned up Unix (LF) end-of-lines), and “Tabs” (replaced Tabs with spaces).

QClean Command-Line Parameters

QClean takes the following command-line parameters:

[root-dir] . root directory to clean (relative or absolute)
-h help (show help message and exit)
-q query only (no cleanup when -q present)
-r check also read-only files
-l[limit] 80 line length limit (not checked when -l absent)

QClean Features

QClean fixes the following whitespace problems:

  • removing of all trailing whitespace (see figure above 1)
  • applying consistent End-Of-Line convention (either Unix (LF) or DOS (CRLF) see figure above 2)
  • replacing Tabs with spaces (untabify, see figure above 2)
  • optionally, scan the source code for long lines exceeding the specified limit (-l option, default 80 characters per line).

Long Lines

QClean can optionally check the code for long lines of code that exceed a specified limit (80 characters by default) to reduce the need to either wrap the long lines (which destroys indentation), or the need to scroll the text horizontally. (All GUI usability guidelines universally agree that horizontal scrolling of text is always a bad idea.) In practice, the source code is very often copied-and-pasted and then modified, rather than created from scratch. For this style of editing, it’s very advantageous to see simultaneously and side-by-side both the original and the modified copy. Also, differencing the code is a routinely performed action of any VCS (Version Control System) whenever you check-in or merge the code. Limiting the line length allows to use the horizontal screen real estate much more efficiently for side-by-side-oriented text windows instead of much less convenient and error-prone top-to-bottom differencing.

QClean File Types

QClean applies the following rules for cleaning the whitespace depending on the file types:

.c Unix (LF) remove remove check
.h Unix (LF) remove remove check
.cpp Unix (LF) remove remove check
.hpp Unix (LF) remove remove check
.s Unix (LF) remove remove check
.asm Unix (LF) remove remove check
.lnt Unix (LF) remove remove check
.txt DOS (CR,LF) remove remove don’t check
.md DOS (CR,LF) remove remove don’t check
.bat DOS (CR,LF) remove remove don’t check
.ld Unix (LF) remove remove check
.tcl Unix (LF) remove remove check
.py Unix (LF) remove remove check
.java Unix (LF) remove remove check
Makefile Unix (LF) remove leave check
.mak Unix (LF) remove leave check
.html Unix (LF) remove remove don’t check
.htm Unix (LF) remove remove don’t check
.php Unix (LF) remove remove don’t check
.dox Unix (LF) remove remove don’t check
.m Unix (LF) remove remove check

The cleanup rules specified in the table above can be easily customized by editing the array l_fileTypes in the qclean/source/main.c file. Also, you can change the Tab sizeby modifying the TAB_SIZE constant (currently set to 4) as well as the default line-limit by modifying the LINE_LIMIT constant (currently set to 80) at the top of the the qclean/source/main.c file. Of course, after any such modification, you need to re-build the QClean executable and copy it into the qtools/bin directory.

Note: For best code portability, QClean enforces the consistent use of the specified End-Of-Line convention (typically Unix (LF)), regardless of the native EOL of the platform. The DOS/Windows EOL convention (CR,LF) is typically not applied because it causes compilation problems on Unix-like systems (Specifically, the C preprocessor doesn’t correctly parse the multi-line macros.) On the other hand, most DOS/Windows compilers seem to tolerate the Unix EOL convention without problems.


QClean is very simple to use (no parameters are needed in most cases) and is fast (it can easily cleanup hundreds of files per second). All this is designed so that you can use QClean frequently. In fact, the use of QClean after editing your code should become part of your basic hygiene–like washing hands after going to the bathroom.

The Best Christmas Present for a Nerd

Wednesday, December 5th, 2012 Miro Samek

Christmas is right around the corner and if you wonder about the presents, I have just an idea for you. No, it is not the new iPad, Galaxy S3 phone, or any of the new “ultrabooks”. In fact, this is exactly the opposite. My present idea is to boost your productivity in creating “content”, not merely consuming it.

And when it comes to creating anything with a computer, you need a big screen–the bigger the better. In fact, I’d recommend that you get yourself two new monitors. And don’t think small. How about two 27″, 1920x1080p full HD, LED-lit panes? You can get those for under $300 each, so a pair will still cost you less than a new iPad.

I got such a setup a few months ago, and now I’m absolutely convinced that this has been the best investment in my productivity–better than a faster CPU or a solid-state disk. I really can’t benefit from my machine being faster–that’s not what wastes my time. But I sure can use more screen, to read the documentation two pages at a time, and to see a complete IDE or a modeling tool on the other screen (modeling tools absolutely love big screens!).

The picture of my desk shows my setup. I have two 27″ HP 2711x 1080p monitors connected to an HP dv6 laptop. One monitor is connected via the HDMI cable and the other via the analog VGI cable. I don’t see any degradation in image quality on the VGA-driven monitor.

Dual Monitors

As you can see in the picture, I’ve placed my monitors on 6″ stands above my desk ($25 each). This is actually quite important, because too many people place their screens too low for comfortable work. (Using a laptop without a stand and additional keyboard is absolutely the worst!)

So, here it is: my Christmas present idea for a nerd. Write a letter to Santa about it, and maybe he will shove it down your chimney? (Only if you are good, that is!)