Dr. Dobb's Journal - March 2008 - (Page 61)

• cURL (curl.haxx.se) • wget (www.gnu.org/software/wget/) • Netcat (netcat.sourceforge.net) Once you retrieve a page, you can parse its content using the ever-useful combination of sed/awk/grep and regular expressions. So suppose you want to be notified when a new version of Microsoft’s Process Explorer is released. Figure 1 is the web page for Process Explorer showing the version information you wish to monitor (v11.04) (www.microsoft.com/technet/sysinternals/ utilities/processexplorer.mspx). The following one-line script determines the current version of Microsoft’s Process Explorer. I ran this from a cygwin (www.cygwin.com) bash session: wget -qOhttp://www.microsoft.com/technet/ sysinternals/utilities/ processexplorer.mspx | sed 's/ ]*>//g' - | grep -o -m1 -P "v[\d\.]{4,}" ing e-mail notifications, and so on). However, there are inherent limitations to this command-line approach: • Checking and processing multiple websites must be done sequentially. • A nonresponsive website can slow down the entire process if you check multiple websites sequentially. • Reviewing, sorting, and filtering results requires additional work. • Skipping a specific website from a set of websites to monitor is problematic. UI Example With all this in mind, I created a graphical Java application to overcome the limitations I encountered when doing command-line Figure 1: Web page for Process Explorer. PC Presents Bug of the Month #1411 l. st ge y oo nd on sl e t ki e l uou ar an Th n tw m nti of . . co sed s of . ti ry ver to ad e his th in -lint 8.0 for C/C++ #include The output (at this writing) is as expected: v11.04. Note that: • The wget -qO- option causes the retrieved page to be sent to stdout instead of a file. • The sed 's/ ]*>//g' command deletes HTML tags (any text beginning with “ ”). Because you’re after the page content, you dutifully ignore HTML tags. • The grep -o -m1 -P "v[\d\.]{4,}" command outputs the first match of the given Perl regular expression. You look for the “v” character followed by four or more digits or “.” characters. The script relies on a common editorial pattern: The most current information should appear first, hence the ability to simply use the first match. If the page listed multiple releases in chronologically ascending order, then additional processing would be required to grab the last match instead of the first match. The command-line approach works well and can be readily incorporated into other scripts to provide additional functionality (automatic downloading, send- A politician wants to specialize his speeches for different audiences. But he's getting strange results when speaking to Unions. What went wrong? Visit our web site at www.gimpel.com typedef const char * CS; class Group { public: virtual CS noun(int good) const { return good ? "good" : "bad"; } }; class Women : public Group { public: CS noun(int good) const { return good ? "motherhood" : "crime"; } }; class Unions : public Group { public: CS noun(bool good) const { return good ? "high wages" : "unemployment"; } }; void speech( Group const *g ) { printf( "I favor %s but I oppose %s\n", g->noun(1), g->noun(0) ); } Plus Our Traditional C/C++ Warnings: Uninitialized variables, inherited non-virtual destructors, strong type mismatches,ill-formed macros, inadvertent name-hiding, suspicious expressions, etc., etc. Full Language Support for ANSI/ISO C and C++. PC-lint for C/C++ will catch this and many other bugs. It will analyze a mixed suite of C and C++ modules to uncover bugs, glitches, quirks and inconsistencies. Not your Grandpa’s lint: PC-lint has introduced several spectacular and revolutionary innovations in the art of static program analysis. Taking clues from initializers, assignments, and conditionals, variable and member values are tracked, enabling reports on potential uses of null pointers and out-of-bounds subscripts. New with Version 8: Interfunction value tracking – Actual argument values are used to initialize parameters; return values are computed; a multipass operation (you control the number of passes) allows you to plumb the depths of function behavior to arbitrary levels. PC-lint for C/C++ Numerous compilers/ libraries supported. Runs on Windows, MS-DOS, and OS/2. $239 FlexeLint for C/C++ The same great product for other operating systems. Runs on all UNIX systems, VMS, mainframes, etc. Distributed in shrouded C source form. Call for pricing. 30 Day Money Back Guarantee G i m p e l S o f t wa r e Serving the C/C++ Community for 22 Years. CALL TODAY (610) 584-4261 Or FAX (610) 584-4266 www.gimpel.com PC-lint and FlexeLint are trademarks of Gimpel Software March 2008 l www.ddj.com l Dr. Dobb’s Journal 61 http://curl.haxx.se http://www.gnu.org/software/wget/ http://netcat.sourceforge.net http://www.microsoft.com/technet/sysinternals/utilities/processexplorer.mspx http://www.microsoft.com/technet/sysinternals/utilities/processexplorer.mspx http://www.cygwin.com http://www.gimpel.com http://www.gimpel.com http://www.gimpel.com http://www.ddj.com

Table of Contents Feed for the Digital Edition of Dr. Dobb's Journal - March 2008

Dr. Dobb's Journal - March 2008 Contents Hmmmm Alia Vox Developer Diaries Developer’s Notebook Social Networks and Software Development Conversations Detecting Bugs in Safety-Critical Code Change Code Without Fear Continuous Integration and Performance Testing Wt: A Web Toolkit Automating Release Notifications The Agile Edge Effective Concurrency Swaine’s Flames

Dr. Dobb's Journal - March 2008

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