🌐 Mailman 3 September 2007 - Tutor - python.org

Send binary/hex data to a TCP socket
by Tod Haren July 19, 2011

July 19, 2011

I need to send a server at the other end of a socket a 36 byte "frame", where each byte represents a specific field in the custom data structure. (If there are any Ham operators reading this, I'm talking about the AGW Packet Engine) The documentation for the server says to initialize each field to a binary zero(0x00). How do I get a binary zero in Python? The next step is to send this all to the server and subsequently receive a similarly formated frame. A very basic frame looks something like this(modified from documentation): |00 00 00 00 4D 00 00 00 00 00 00 00 00 00 00 00 |....M........... |00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................ |00 00 00 00 |.... My problem is that hex(0) return '0x0' and hex(ord('M')) returns '0x4d'. If I concatonate these all together then the socket receives 109 bytes instead of 36. The documentation examples are in C++, so they are little help to me. The examples make use of the MoveMemory function for building the frames, but I'm clueless what that does. Pseudo code for the frame above: l = [] for i in xrange(36): l.append(hex(0)) l[4]=hex(ord('M')) d='' d=d.join(l) #I need some other data type to send besides a string! sock.send(d) #send the 36 bytes to the socket Any pointers or references would be greatly appreciated.

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Tracking time
by Michael Key Jan. 6, 2010

Jan. 6, 2010

I am trying to develop a project tracking program that would allow you to track hours and minutes spent on several different projects and store he data in a database for printing. Any help would be appreciated. Mike

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Learning Python
by Fred P Dec. 13, 2009

Dec. 13, 2009

Hey Everyone, I am completely new at python, but not new to programming or scripting. I have a couple of years of LUA scripting experience, about a year of C++ classes, and used to be very efficient at c-shell scripting in unix. My question for you guys: 1) How do I get Started? 2) Recommend any specific Books? 3) Any online tutors/ forums that would benefit a newbie 4) Any online classes that teach python? I have taken online c++ courses, and found them helpful. I was hoping to find something for python. My main objective is to write scripts for the following type of applications File management, file copies/syncs/ compares Text manipulation - like parsing text files to replace or augment specific values Integration into current applications to write redundant routines and maybe some day plugins I am not even sure what else, but I do know that every time i think of something that we need at work, other people say, "That would be a good task for a python script" and I would eventually like to be able to do something about that. Thanks Fred

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difflib.SequenceMatcher with get_matching_blocks is incorrect
by Thomas Nov. 5, 2007

Nov. 5, 2007

I'm trying to write a program to test someone's typing speed and show them their mistakes. However I'm getting weird results when looking for the differences in longer (than 100 chars) strings: import difflib # a tape measure string (just makes it easier to locate a given index) a = '1-3-5-7-9-12-15-18-21-24-27-30-33-36-39-42-45-48-51-54-57-60-63-66-69-72-75-78-81-84-87-90-93-96-99-103-107-111-115-119-123-127-131-135-139-143-147-151-155-159-163-167-171-175-179-183-187-191-195--200' # now with a few mistakes b = '1-3-5-7-l-12-15-18-21-24-27-30-33-36-39o42-45-48-51-54-57-60-63-66-69-72-75-78-81-84-8k-90-93-96-9l-103-107-111-115-119-12b-1v7-131-135-139-143-147-151-m55-159-163-167-a71-175j179-183-187-191-195--200' s = difflib.SequenceMatcher(None, a ,b) ms = s.get_matching_blocks() print ms [(0, 0, 8), (200, 200, 0)] Have I made a mistake or is this function designed to give up when the input strings get too long? Thanks in advance, Thomas

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largest and smallest numbers
by Christopher Spears Oct. 15, 2007

Oct. 15, 2007

One of the exercises from Core Python Programmng (2nd Edition) asks me to determine the largest and smallest integers, float, and complex numbers my system can handle. Using python.org and Google, I have discovered my system's largest and smallest ingtegers: >>> import sys >>> sys.maxint 2147483647 >>> -sys.maxint - 1 -2147483648 How can I find the largest float and complex numbers?

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Need help speeding up algorithm.
by Ian Witham Oct. 2, 2007

Oct. 2, 2007

Hello, I am attempting to do this <https://www.spoj.pl/problems/FCTRL/> project for the Sphere Online Judge. I think my program is getting the right answer, however it exceeds the 6s time limit on the judge machine. Here is my code: ############ import sys testnums = [] tests = int(sys.stdin.readline()) for count in xrange(tests): testnums.append(int(sys.stdin.readline())) for d in testnums: maxer = int(d ** .2) + 1 g = sum(d / (5 ** x) for x in xrange(1, maxer)) sys.stdout.write('%d\n' % g) ############ Any ideas on how to speed this up? Also, if anyone is familiar with the Online Judge system, am I correct in gathering all of the input first and then providing the output? Or should I be providing output after each input? Any help appreciated, Ian.

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creating the equivalent of string.strip()
by Christopher Spears Oct. 2, 2007

Oct. 2, 2007

I'm working out of chapter 6 of Core Python Programming (2nd Edition). For one problem, I am supposed to write a script that is the equivalent of string.strip(). Obviously, using any version of string.strip() defeats the purpose of the exercise. I'm not sure how to proceed. My biggest stumbling block is how to detect the leading and trailing whitespace. If I wanted to remove all whitespace in a string, I would probably break the string into its individual components, cycle through the string, detect the whitespace, and remove them. Any hints?

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Disable keyboard/mouse input on windows?
by Trey Keown Oct. 1, 2007

Oct. 1, 2007

Hey everybody, I was wondering, how could I disable all keyboard/mouse input for the whole windows system while I have a video playing? So the user can't press, for example, the super key [one with windows logo on it], and have the windows menu pop up? Could this be accomplished somehow through system hooks? Thanks

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Re: [Tutor] CGI File Woes
by wormwood_3 Oct. 1, 2007

Oct. 1, 2007

Those examples were a lot of help Martin. Turned out the only issue was that I did not have this line right: print "Content-type: text/html\n\n" With that form, it loaded just fine. It had been running fine from the terminal, but without this line being right, Apache did not know what to do with it. I had spoken with my web-hosting provider, but since I had a shared account I was unable to view the server logs. And the person helping me knew nothing about Python (he kept slipping and calling it PHP actually, to my dismay and chagrin:-) ). Thanks for all the help, Alan and Martin. -Sam _________________ ----- Original Message ---- From: Martin Walsh <mwalsh(a)groktech.org> To: tutor(a)python.org Sent: Sunday, September 30, 2007 1:07:02 PM Subject: Re: [Tutor] CGI File Woes No doubt cgitb is a great tool for debugging cgi, but IIUC there are at least two instances when you will not get the pretty printed tracebacks in the browser when using cgitb. One is after, what I would call, a 'compile time' exception such as SyntaxError, in your python code. The other is when the python code runs without exception, but you have not separated the header and the document content with a newline. At least, I have found these to be true when using apache-cgi. Consider the following examples: #!/usr/bin/env python # raises a SyntaxError import cgi import cgitb; cgitb.enable() print "Content-type: text/html\n\n" # NOTE: purposeful misspelling of the print statement prin "<html><body><p>Hello, world!</p></body></html>" # the code above will produce a server 500, with apache # complaining about "premature end of script headers" ... #!/usr/bin/env python # good python, bad data import cgi import cgitb; cgitb.enable() print "Content-type: text/html" print "<html><body><p>Hello, world!</p></body></html>" # this is syntactically correct python, and will # run from the command line, but the html header # and html content have no separation, so apache # will consider all of it to be header info, resulting # in another server 500, "malformed header" As others have advised, under these circumstances you can review the apache error log (if your webhost allows it). Or roll-your-own logging equivalent, and run your cgi from a terminal to catch SyntaxErrors and the like. HTH, Marty _______________________________________________ Tutor maillist - Tutor(a)python.org http://mail.python.org/mailman/listinfo/tutor

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CGI File Woes
by wormwood_3 Sept. 30, 2007

Sept. 30, 2007

Hello all, I am working on a very simple CGI script. The site I want to use it on is a shared linux host, but I confirmed that .py files in the right dir with the right permissions and shebang execute just fine, Hello World sort of tests were successful. So now something a little more involved: #!/usr/bin/python2.4 import cgitb; cgitb.enable() thefile = open("template.html", "r") templatestuff = thefile.read() thefile.close() print "Content-Type: text/html" if templatestuff: print "Found it" title1 = "I am a title!" body1 = "I am some hot content" print templatestuff % (title1, body1) "template.html" is in the same dir, and is simply: http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html> <html> <head> <title> %s </title> </head> <body> %s </body> </html> If I run this script without the 3 lines after the import line, it works fine (namely I get an error that templatestuff is not defined, as would be expected). With those lines however, I am getting a 500 Internal Server Error. Since I am not shown an error page with cgitb, this would likely mean a syntax error. However, if I run the script locally, it works just fine, printing out the HTML with variables filled in. Now for the odd part: If I change that open line to "thefile = open("asdas", "r")", I get "IOError: [Errno 2] No such file or directory: 'asdas' ". So it seems the script is finding the template file when I have it as above, but is throwing something when it tries to open it. I have confirmed the file has the right permissions, I have even tried it with all permissions set on that file. I am just totally baffled why I cannot open any files from the script. Any ideas? -Sam

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