phimuemue - Developer IT

HTML form with multiple submit options

- by phimuemue

Hi, I'm trying to create a small web app that is used to remove items from a MySQL table. It just shows the items in a HTML table and for each item a button [delete]: item_1 [delete] item_2 [delete] ... item_N [delete] To achieve this, I dynamically generate the table via PHP into a HTML form. This form has then obviously N [delete]-buttons. The form should use the POST-method for transfering data. For the deletion I wanted to submit the ID (primary key in the MySQL table) of the corresponding item to the executing php skript. So I introduced hidden fields (all these fields have the name='ID' that store the ID of the corresponding item. However, when pressing an arbitrary [delete], it seems to submit always just the last ID (i.e. the value of the last ID hidden field). Is there any way to submit just the ID field of the corresponding item without using multiple forms? Or is it possible to submit data from multiple forms with just one submit-button? Or should I even choose any completly different way? The point why I want to do it in just one single form is that there are some "global" parameters that shall not be placed next to each item, but just once for the whole table.

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P-NP-Problem: What are the most promising methods?

- by phimuemue

Hello everybody, I know that P=NP has not been solved up to now, but can anybody tell me something about the following: What are currently the most promising mathematical / computer scientific methods that could be helpful to tackle this problem? Or are there even none such methods known to be potentially helpful up to now? Is there any (free) compendium on this topic where I can find all / most of the research done in this area?

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Emacs 23: Selection not highlighted

- by phimuemue

I installed Ubuntu 10.04, and with it came Emacs 23. If I want to select text in Emacs, that works perfectly fine except the fact that the region is not highlighted. However, this only happens, if I try to make a region using the keyboard. If I select something with the mouse, it is highlighted as usual. Does anybody know, why the region is not highlighted and how to fix that?

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P=NP?-Problem: What are the most promising methods?

- by phimuemue

Hello everybody, I know that P=NP has not been solved up to now, but can anybody tell me something about the following: What are currently the most promising mathematical / computer scientific methods that could be helpful to tackle this problem? Or are there even none such methods known to be potentially helpful up to now? Is there any (free) compendium on this topic where I can find all / most of the research done in this area?

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C++/g++: Concurrent programm

- by phimuemue

Hi, I got a C++ program (source) that is said to work in parallel. However, if I compile it (I am using Ubuntu 10.04 and g++ 4.4.3) with g++ and run it, one of my two CPU cores gets full load while the other is doing "nothing". So I spoke to the one who gave me the program. I was told that I had to set specific flags for g++ in order to get the program compiled for 2 CPU cores. However, if I look at the code I'm not able to find any lines that point to parallelism. So I have two questions: Are there any C++-intrinsics for multithreaded applications, i.e. is it possible to write parallel code without any extra libraries (because I did not find any non-standard libraries included)? Is it true that there are indeed flags for g++ that tell the compiler to compile the program for 2 CPU cores and to compile it so it runs in parallel (and if: what are they)?

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Algorithm: Removing as few elements as possible from a set in order to enforce no subsets.

- by phimuemue

Hello, I got a problem which I do not know how to solve: I have a set of sets A = {A_1, A_2, ..., A_n} and I have a set B. The target now is to remove as few elements as possible from B (creating B'), such that, after removing the elements for all 1 <= i <= n, A_i is not a subset of B'. For example, if we have A_1 = {1,2}, A_2 = {1,3,4}, A_3={2,5}, and B={1,2,3,4,5}, we could e.g. remove 1 and 2 from B (that would yield B'={3,4,5}, which is not a superset of one of the A_i). Does anybody know an algorithm for determining the (minimal number of) elements to be removed?

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SVN Version Rollback Question

- by phimuemue

Hello, I'm using SVN (TortoiseSVN) and often came into the following situation: I wanted to discard any changes since a specific (old) revision and turn all files back to this specific (old) version. Then I wanted to work further as if this specific (old) revision was the newest one, i.e. I wanted to be able to commit the specific old revision as a new revision. I found several solutions for this problem (for example stackoverflow.com/questions/402159/roll-back-or-revert-entire-svn-repository-to-an-older-revision or rustyrazorblade.com/2007/04/how-to-roll-back-commits-to-an-earlier-version-of-a-repository-in-svn/). However, I wonder if there is a simple way to roll back to a specific revision. I thought version control is just good for such things (or am I misunderstanding something?). Is there a simple command/button/etc. that takes an updates my local repository to an old revision and declares it to be the newest one? Since I suppose that there is no "built-in" function to do this, I wanted to know what reason lead the developers to the decision not to integrate this feature. Does anybody know this?

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Emacs: Auto Complete for C++

- by phimuemue

Hello, i found this autocompletion for Emacs: http://www.emacswiki.org/emacs/AutoComplete, but I can't find what languages it supports. I want to use it particular for C++-autocompletion. Has anybody experience with this?

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How does delete[] (C++) work?

- by phimuemue

In C++ the size of an array is not stored in the array itself, but how does delete[] determine how many bytes to free? Is every array terminated by \0 or something similar?

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