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  • how to append a string to next line in perl

    - by tprayush
    hi all , i have a requirement like this.. this just a sample script... $ cat test.sh #!/bin/bash perl -e ' open(IN,"addrss"); open(out,">>addrss"); @newval; while (<IN>) { @col_val=split(/:/); if ($.==1) { for($i=0;$i<=$#col_val;$i++) { print("Enter value for $col_val[$i] : "); chop($newval[$i]=<STDIN>); } $str=join(":"); $_="$str" print OUT; } else { exit 0; } } close(IN); close(OUT); ' when i run this scipt... $ ./test.sh Enter value for NAME : abc Enter value for ADDRESS : asff35 Enter value for STATE : XYZ Enter value for CITY : EIDHFF Enter value for CONTACT : 234656758 $ cat addrss NAME:ADDRESS:STATE:CITY:CONTACT abc:asff35:XYZ:EIDHFF:234656758 when ran it second time $ cat addrss NAME:ADDRESS:STATE:CITY:CONTACT abc:asff35:XYZ:EIDHFF:234656758ioret:56fgdh:ghdgh:afdfg:987643221 ## it is appended in the same line... i want it to be added to the next line..... NOTE: i want to do this by explitly using the filehandles in perl....and not with redirection operators in shell. please help me!!!

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  • LINQ .Cast() extension method fails but (type)object works.

    - by Ben Robinson
    To convert between some LINQ to SQL objects and DTOs we have created explicit cast operators on the DTOs. That way we can do the following: DTOType MyDTO = (LinqToSQLType)MyLinq2SQLObj; This works well. However when you try to cast using the LINQ .Cast() extension method it trows an invalid cast exception saying cannot cast type Linq2SQLType to type DTOType. i.e. the below does not work List<DTO.Name> Names = dbContact.tNames.Cast<DTO.Name>() .ToList(); But the below works fine: DAL.tName MyDalName = new DAL.tName(); DTO.Name MyDTOName = (DTO.Name)MyDalName; and the below also works fine List<DTO.Name> Names = dbContact.tNames.Select(name => (DTO.Name)name) .ToList(); Why does the .Cast() extension method throw an invalid cast exception? I have used the .Cast() extension method in this way many times in the past and when you are casting something like a base type to a derived type it works fine, but falls over when the object has an explicit cast operator.

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  • Is this overly clever or unsafe?

    - by Liberalkid
    I was working on some code recently and decided to work on my operator overloading in c++, because I've never really implemented it before. So I overloaded the comparison operators for my matrix class using a compare function that returned 0 if LHS was less than RHS, 1 if LHS was greater than RHS and 2 if they were equal. Then I exploited the properties of logical not in c++ on integers, to get all of my compares in one line: inline bool Matrix::operator<(Matrix &RHS){ return ! (compare(*this,RHS)); } inline bool Matrix::operator>(Matrix &RHS){ return ! (compare((*this),RHS)-1); } inline bool Matrix::operator>=(Matrix &RHS){ return compare((*this),RHS); } inline bool Matrix::operator<=(Matrix &RHS){ return compare((*this),RHS)-1; } inline bool Matrix::operator!=(Matrix &RHS){ return compare((*this),RHS)-2; } inline bool Matrix::operator==(Matrix &RHS){ return !(compare((*this),RHS)-2); } Obviously I should be passing RHS as a const, I'm just probably not going to use this matrix class again and I didn't feel like writing another function that wasn't a reference to get the array index values solely for the comparator operation.

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  • Use cell formatting (e.g. "Good", "Bad", "Neutral") in formulas?

    - by ngm
    I am compiling a comparison of different pieces of software in an Excel spreadsheet. It is a big long list of features (the rows), with each column being one of the applications I'm evaluating. I've used styles to visually show how well each product meets each feature, as well as the importance of that feature, and now I'm wondering if there's a way I can use those annotations in a formula. The table is like: . | Product A | Product B | Product C Feature A | blah blah blah Feature B | blah blah blah Feature C | blah blah blah .... | .... | etc | Where I've put 'blah' in the table above, in my actual spreadsheet is (potentially lengthy) descriptive text explaining something about this feature in the given product. I've then used the styles "Good", "Neutral" and "Bad" to visually annotate the description, to show how well each product meets that feature. For each feature I've also used the styles Accent4, 60% Accent4, 40% Accent4, etc, to annotate the importance of each feature. Now I'm wondering if somehow I can use those styles (the annotations) to tot up a total score for each product. e.g., Score for feature A = valueof(60% Accent4) * valueof(Good) Is it possible at all?

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  • Linq-to-XML explicit casting in a generic method

    - by vlad
    I've looked for a similar question, but the only one that was close didn't help me in the end. I have an XML file that looks like this: <Fields> <Field name="abc" value="2011-01-01" /> <Field name="xyz" value="" /> <Field name="tuv" value="123.456" /> </Fields> I'm trying to use Linq-to-XML to get the values from these fields. The values can be of type Decimal, DateTime, String and Int32. I was able to get the fields one by one using a relatively simple query. For example, I'm getting the 'value' from the field with the name 'abc' using the following: private DateTime GetValueFromAttribute(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == "abc" select (DateTime)field.Attribute("value")).FirstOrDefault() } this is placed in a separate function that simply returns this value, and everything works fine (since I know that there is only one element with the name attribute set to 'abc'). however, since I have to do this for decimals and integers and dates, I was wondering if I can make a generic function that works in all cases. this is where I got stuck. here's what I have so far: private T GetValueFromAttribute<T>(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == attName select (T)field.Attribute("value").Value).FirstOrDefault(); } this doesn't compile because it doesn't know how to convert from String to T. I tried boxing and unboxing (i.e. select (T) (Object) field.Attribute("value").Value but that throws a runtime Specified cast is not valid exception as it's trying to convert the String to a DateTime, for instance. Is this possible in a generic function? can I put a constraint on the generic function to make it work? or do I have to have separate functions to take advantage of Linq-to-XML's explicit cast operators?

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  • How to support comparisons for QVariant objects containing a custom type?

    - by Tyler McHenry
    According to the Qt documentation, QVariant::operator== does not work as one might expect if the variant contains a custom type: bool QVariant::operator== ( const QVariant & v ) const Compares this QVariant with v and returns true if they are equal; otherwise returns false. In the case of custom types, their equalness operators are not called. Instead the values' addresses are compared. How are you supposed to get this to behave meaningfully for your custom types? In my case, I'm storing an enumerated value in a QVariant, e.g. In a header: enum MyEnum { Foo, Bar }; Q_DECLARE_METATYPE(MyEnum); Somewhere in a function: QVariant var1 = QVariant::fromValue<MyEnum>(Foo); QVariant var2 = QVariant::fromValue<MyEnum>(Foo); assert(var1 == var2); // Fails! What do I need to do differently in order for this assertion to be true? I understand why it's not working -- each variant is storing a separate copy of the enumerated value, so they have different addresses. I want to know how I can change my approach to storing these values in variants so that either this is not an issue, or so that they do both reference the same underlying variable. It don't think it's possible for me to get around needing equality comparisons to work. The context is that I am using this enumeration as the UserData in items in a QComboBox and I want to be able to use QComboBox::findData to locate the item index corresponding to a particular enumerated value.

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  • F# How to tokenise user input: separating numbers, units, words?

    - by David White
    I am fairly new to F#, but have spent the last few weeks reading reference materials. I wish to process a user-supplied input string, identifying and separating the constituent elements. For example, for this input: XYZ Hotel: 6 nights at 220EUR / night plus 17.5% tax the output should resemble something like a list of tuples: [ ("XYZ", Word); ("Hotel:", Word); ("6", Number); ("nights", Word); ("at", Operator); ("220", Number); ("EUR", CurrencyCode); ("/", Operator); ("night", Word); ("plus", Operator); ("17.5", Number); ("%", PerCent); ("tax", Word) ] Since I'm dealing with user input, it could be anything. Thus, expecting users to comply with a grammar is out of the question. I want to identify the numbers (could be integers, floats, negative...), the units of measure (optional, but could include SI or Imperial physical units, currency codes, counts such as "night/s" in my example), mathematical operators (as math symbols or as words including "at" "per", "of", "discount", etc), and all other words. I have the impression that I should use active pattern matching -- is that correct? -- but I'm not exactly sure how to start. Any pointers to appropriate reference material or similar examples would be great.

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  • Haskel dot (.) and dollar ($) composition: correct use.

    - by Robert Massaioli
    I have been reading Real World Haskell and I am nearing the end but a matter of style has been niggling at me to do with the (.) and ($) operators. When you write a function that is a composition of other functions you write it like: f = g . h But when you apply something to the end of those functions I write it like this: k = a $ b $ c $ value But the book would write it like this: k = a . b . c $ value Now to me they look functionally equivalent, they do the exact same thing in my eyes. However, the more I look, the more I see people writing their functions in the manner that the book does: compose with (.) first and then only at the end use ($) to append a value to evaluate the lot (nobody does it with many dollar compositions). Is there a reason for using the books way that is much better than using all ($) symbols? Or is there some best practice here that I am not getting? Or is it superfluous and I shouldn't be worrying about it at all? Thanks.

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  • Haskell function composition (.) and function application ($) idioms: correct use.

    - by Robert Massaioli
    I have been reading Real World Haskell and I am nearing the end but a matter of style has been niggling at me to do with the (.) and ($) operators. When you write a function that is a composition of other functions you write it like: f = g . h But when you apply something to the end of those functions I write it like this: k = a $ b $ c $ value But the book would write it like this: k = a . b . c $ value Now to me they look functionally equivalent, they do the exact same thing in my eyes. However, the more I look, the more I see people writing their functions in the manner that the book does: compose with (.) first and then only at the end use ($) to append a value to evaluate the lot (nobody does it with many dollar compositions). Is there a reason for using the books way that is much better than using all ($) symbols? Or is there some best practice here that I am not getting? Or is it superfluous and I shouldn't be worrying about it at all? Thanks.

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  • How would I compare two Lists(Of <CustomClass>) in VB?

    - by Kumba
    I'm working on implementing the equality operator = for a custom class of mine. The class has one property, Value, which is itself a List(Of OtherClass), where OtherClass is yet another custom class in my project. I've already implemented the IComparer, IComparable, IEqualityComparer, and IEquatable interfaces, the operators =, <>, bool and not, and overriden Equals and GetHashCode for OtherClass. This should give me all the tools I need to compare these objects, and various tests comparing two singular instances of these objects so far checks out. However, I'm not sure how to approach this when they are in a List. I don't care about the list order. Given: Dim x As New List(Of OtherClass) From {New OtherClass("foo"), New OtherClass("bar"), New OtherClass("baz")} Dim y As New List(Of OtherClass) From {New OtherClass("baz"), New OtherClass("foo"), New OtherClass("bar")} Then (x = y).ToString should print out True. I need to compare the same (not distinct) set of objects in this list. The list shouldn't support dupes of OtherClass, but I'll have to figure out how to add that in later as an exception. Not interested in using LINQ. It looks nice, but in the few examples I've played with, adds a performance overhead in that bugs me. Loops are ugly, but they are fast :) A straight code answer is fine, but I'd like to understand the logic needed for such a comparison as well. I'm probably going to have to implement said logic more than a few times down the road.

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  • Reflection and Operator Overloads in C#

    - by TenshiNoK
    Here's the deal. I've got a program that will load a given assembly, parse through all Types and their Members and compile a TreeView (very similar to old MSDN site) and then build HTML pages for each node in the TreeView. It basically takes a given assembly and allows the user to create their own MSDN-like library for it for documentation purposes. Here's the problem I've run into: whenever an operator overload is encounted in a defined class, reflection returns that as a "MethodInfo" with the name set to something like "op_Assign" or "op_Equality". I want to be able to capture these and list them properly, but I can't find anything in the MethodInfo object that is returned to accurately identify that I'm looking at an operator. I definitely don't want to just capture everything that starts with "op_", since that will most certainly (at some point) will pick up a method it's not supposed to. I know that other methods and properties that are "special cases" like this one have the "IsSpecialName" property set, but appearantly that's not the case with operators. I've been scouring the 'net and wracking my brain to two days trying to figure this one out, so any help will be greatly appreciated.

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  • How can I avoid encoding mixups of strings in a C/C++ API?

    - by Frerich Raabe
    I'm working on implementing different APIs in C and C++ and wondered what techniques are available for avoiding that clients get the encoding wrong when receiving strings from the framework or passing them back. For instance, imagine a simple plugin API in C++ which customers can implement to influence translations. It might feature a function like this: const char *getTranslatedWord( const char *englishWord ); Now, let's say that I'd like to enforce that all strings are passed as UTF-8. Of course I'd document this requirement, but I'd like the compiler to enforce the right encoding, maybe by using dedicated types. For instance, something like this: class Word { public: static Word fromUtf8( const char *data ) { return Word( data ); } const char *toUtf8() { return m_data; } private: Word( const char *data ) : m_data( data ) { } const char *m_data; }; I could now use this specialized type in the API: Word getTranslatedWord( const Word &englishWord ); Unfortunately, it's easy to make this very inefficient. The Word class lacks proper copy constructors, assignment operators etc.. and I'd like to avoid unnecessary copying of data as much as possible. Also, I see the danger that Word gets extended with more and more utility functions (like length or fromLatin1 or substr etc.) and I'd rather not write Yet Another String Class. I just want a little container which avoids accidental encoding mixups. I wonder whether anybody else has some experience with this and can share some useful techniques. EDIT: In my particular case, the API is used on Windows and Linux using MSVC 6 - MSVC 10 on Windows and gcc 3 & 4 on Linux.

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  • Database schema to store AND, OR relation, association

    - by user455387
    Many thanks for your help on this. In order for an entreprise to get a call for tender it must meet certain requirements. For the first example the enterprise must have a minimal class 4, and have qualification 2 in sector 5. Minimal class is always one number. Qualification can be anything (single, or multiple using AND, OR logical operators) I have created tables in order to map each number to it's given name. Now I need to store requirements in the database. minimal class 4 Sector Qualification 5.2 minimal class 2 Sector Qualifications 3.9 and 3.10 minimal class 3 Sector Qualifications 6.1 or 6.3 minimal class 1 Sector Qualifications (3.1 and 3.2) or 5.6 class Domain < ActiveRecord::Base has_many :domain_classes has_many :domain_sectors has_many :sector_qualifications, :through => :domain_sectors end class DomainClass < ActiveRecord::Base belongs_to :domain end class DomainSector < ActiveRecord::Base belongs_to :domain has_many :sector_qualifications end class SectorQualification < ActiveRecord::Base belongs_to :domain_sector end create_table "domains", :force => true do |t| t.string "name" end create_table "domain_classes", :force => true do |t| t.integer "number" t.integer "domain_id" end create_table "domain_sectors", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_id" end create_table "sector_qualifications", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_sector_id" end

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  • push_back private vectors with 2 methods, one isn't working

    - by jmclem
    I have a class with a private vector of doubles. To access or modify these values, at first I used methods such as void classA::pushVector(double i) { this->vector.push_back(i); } double classA::getVector(int i) { return vector[i]; } This worked for a while until I found I would have to overload a lot of operators for what I needed, so I tried to change it to get and set the vector directly instead of the values, i.e. void classA::setVector(vector<double> vector) { this->vector = vector; } vector<double> classA::getVector() { return vector; } Now, say there is a classB, which has a private classA element, which also has get and set methods to read and write. The problem was when I tried to push back a value to the end vector in classA. void classB::setFirstValue(double first) { this->getClassA().getVector().push_back(first); } This does absolutely nothing to the vector. It remains unchanged and I can't figure out why... Any ideas?

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  • C++ UTF-8 output with ICU

    - by Isaac
    I'm struggling to get started with the C++ ICU library. I have tried to get the simplest example to work, but even that has failed. I would just like to output a UTF-8 string and then go from there. Here is what I have: #include <unicode/unistr.h> #include <unicode/ustream.h> #include <iostream> int main() { UnicodeString s = UNICODE_STRING_SIMPLE("??????"); std::cout << s << std::endl; return 0; } Here is the output: $ g++ -I/sw/include -licucore -Wall -Werror -o icu_test main.cpp $ ./icu_test пÑÐ¸Ð²ÐµÑ My terminal and font support UTF-8 and I regularly use the terminal with UTF-8. My source code is in UTF-8. I think that perhaps I somehow need to set the output stream to UTF-8 because ICU stores strings as UTF-16, but I'm really not sure and I would have thought that the operators provided by ustream.h would do that anyway. Any help would be appreciated, thank you.

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  • Paranormal activity in My Pictures folder: Thumbnail doesn't match actual picture.

    - by Sam152
    After finding an amusing picture on a popular imageboard, I decided to save it. A few days past and I was browsing my images folder when I realised that the thumbnail generated by Windows XP in the thumbnails view did not match the actual image. Here is a comparison image: What's even stranger in this situation is that the parts of the photograph that are different have actually been replaced with what might be the correct background. Furthermore, it is a jpeg (no PNG transparency tricks) that is 343 kilobytes but only 847x847 pixels wide. What could be going on here? Could there be anything malicious in the works, or hidden data? Before anyone asks, I have checked and preformed the following: Deleted Thumbs.db to reload thumbnails. Opened image in different editors. (they appear with the text) Moved image to a different directory. Changed the extension to .rar. All these steps produce the same results. Pre actual posting update: It seems that opening the image in paint, changing the image entirely (deleting entire contents and making a red fill) will still generate the original thumbnail, even after deleting Thumbs.db etc. I'm also hesitant to post the original data, in case there is something malicious or hidden that could be potentially illegal. (Although it would be very beneficial to see if it works on other computers and not just my own).

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  • What apps can you only get on Mac and not Windows?

    - by ytk
    What apps do you absolutely have to use a Mac to run, and there are no decent Windows PC equivalent? This is not a religious war. Please be specific and practical It doesn't have to be a direct 1-2-1 comparison, but overall usefulness to the task I'll start off with a few: KeyNote -- the animations are quite cool and not available in PowerPoint iTune's photo sync -- on Windows it makes copy of all the photos you want to sync, effectively double the space taken up by your photos. On a Mac it's easier as long as you use iPhoto Keychain -- a centralized password manager tied to the OS. The benefit of this is you don't have to set a Master Password (like Firefox) which you need to enter when starting the browser. And it doesn't reveal your password (like Chrome, which makes no effort in hiding the password you have stored in Options) Time Machine -- 0-configuration backup in the background. Easy interface for restoring a file, or even just a contact in the address book. Text-to-speech -- works in any program, and sounds better than Windows computer voice Quick View -- press space bar to preview a file. Windows95 had quick view, but was removed.

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  • moving from WinXP to WinServer in VmWare

    - by Alex
    I have a Vmware machine for.Net application testing. Current setup: Host OS: win7 Guest OS: Right now the guest OS is Win Xp Pro x64, which runs great with just 1 gigabyte of RAM and 10 gigs of disk space. * This part can be skipped * As I said, there was a program that I needed to test, but unfortunately, by default, Vmware installs crappy display drivers(called SVGA II) on XP machines and there is NO way to upgrade them! This resulted in my program's error (the program used SlimDX (DirectX wrapper) to do some stuff..). Eventually I found out that display drivers most certainly is the problem. For example, Windows 7 virtual machine uses SVGA 3D drivers and I have NO problems running my SlimDX-based program. Now, regarding Windows Server 2008! Apparently, WDDM driver is supported by WS2008, which means that I'll be able to install SVGA 3D and to test my DX apps. * end of skip * The questions are: Will WS2008 be as smooth with just 1 gig of RAM just like Win XP was? Will 10 gigs of HDD be enough? Or the server requires more? Will I be able to install .Net ver. 4 on WS2008? Are there any limitations that I need to be aware of as a .Net programmer? EDIT: I was hoping that WS2008 is XP-based, not Vista-vased/W7-based. In comparison, W7 virtual machine with 2 gigs of RAM and 2 proc cores nearly kills my Host OS. Whereas, WinXp runs extremely fast even with 1 core and 1 gig of RAM. That's the main reason why I want to try WS2008..

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  • Ethernet/8P8C crimp contacts bent

    - by Fire Lancer
    (if anyone knows correct terminology please correct). Ive got a (fairly large) number of existing Ethernet cables that over the years many have got damaged connector clips, so got a crimp tool and some new connectors for them. However out of all 4 attempts I have tried, on crimping 2+ of the little copper contacts that bite into the wires have instead just bent to one side, and so gone between the gaps in in the crimp tool... Unless this really is me doing something wrong (what?) I am inclined to blame the hardware, but is this the crimper or the new connectors I got? I tried to take a picture, as you can just about see looking from the left 3rd, 6th, 7th and 8th pins didn't get pushed in, and so don't form a connector. Unfortunately my camera was barely able to focus on it and then this website converted it to a JPEG... Update: Connectors/Cable/Tools: The wires are stranded (looks about 6 and no evidence of being aluminum/not copper), and the pins(?) have 2 little flat spikes lengthways along the cables (I understand to dig into it, while solid core connectors would have like 2 plates designed to go around the core?). Crimper was http://www.amazon.co.uk/gp/product/B0013EXTKK/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1 (seemed to be highly rated, I already had tools for cutting/stripping). Update2: Picture of crimp "prongs" (?) Update3: Side picture of connector Update4: Comparison with old connector. The top (used) connector is one from a few years back (different tool and connectors), the thing that concerns me that it might not be the tool I need to replace is just how thin the pins are on the new one that maybe a tool could legitimately bend some into a gap rather than pushing them in fully? In fact I can move individual pins to the sides significantly with my fingernail, is that normal?

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  • Overhead of calling tiny functions from a tight inner loop? [C++]

    - by John
    Say you see a loop like this one: for(int i=0; i<thing.getParent().getObjectModel().getElements(SOME_TYPE).count(); ++i) { thing.getData().insert( thing.GetData().Count(), thing.getParent().getObjectModel().getElements(SOME_TYPE)[i].getName() ); } if this was Java I'd probably not think twice. But in performance-critical sections of C++, it makes me want to tinker with it... however I don't know if the compiler is smart enough to make it futile. This is a made up example but all it's doing is inserting strings into a container. Please don't assume any of these are STL types, think in general terms about the following: Is having a messy condition in the for loop going to get evaluated each time, or only once? If those get methods are simply returning references to member variables on the objects, will they be inlined away? Would you expect custom [] operators to get optimized at all? In other words is it worth the time (in performance only, not readability) to convert it to something like: ElementContainer &source = thing.getParent().getObjectModel().getElements(SOME_TYPE); int num = source.count(); Store &destination = thing.getData(); for(int i=0;i<num;++i) { destination.insert(thing.GetData().Count(), source[i].getName(); } Remember, this is a tight loop, called millions of times a second. What I wonder is if all this will shave a couple of cycles per loop or something more substantial? Yes I know the quote about "premature optimisation". And I know that profiling is important. But this is a more general question about modern compilers, Visual Studio in particular.

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  • How can I compare the performance of log() and fp division in C++?

    - by Ventzi Zhechev
    Hi, I’m using a log-based class in C++ to store very small floating-point values (as the values otherwise go beyond the scope of double). As I’m performing a large number of multiplications, this has the added benefit of converting the multiplications to sums. However, at a certain point in my algorithm, I need to divide a standard double value by an integer value and than do a *= to a log-based value. I have overloaded the *= operator for my log-based class and the right-hand side value is first converted to a log-based value by running log() and than added to the left-hand side value. Thus the operations actually performed are floating-point division, log() and floating-point summation. My question whether it would be faster to first convert the denominator to a log-based value, which would replace the floating-point division with floating-point subtraction, yielding the following chain of operations: twice log(), floating-point subtraction, floating-point summation. In the end, this boils down to whether floating-point division is faster or slower than log(). I suspect that a common answer would be that this is compiler and architecture dependent, so I’ll say that I use gcc 4.2 from Apple on darwin 10.3.0. Still, I hope to get an answer with a general remark on the speed of these two operators and/or an idea on how to measure the difference myself, as there might be more going on here, e.g. executing the constructors that do the type conversion etc. Cheers!

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  • What are the right questions to ask when deciding whether to use Chef or Puppet?

    - by John Feminella
    I am about to start a new project which will, in part, require deploying many identical nodes of approximately three different classes: Data nodes, which will run sharded instances of MongoDB. Application nodes, which will run instances of a Ruby on Rails application and an older ASP.NET MVC application. Processing nodes, which will run jobs requested by the application nodes. ALl the nodes will run on instances of Ubuntu 10.04, though they will have different packages installed. I have some familiarity with Chef from previous projects, though I don't consider myself an expert. In an effort to do due diligence, I have been investigating alternative possibilities. We have a number of folks in-house who are long-time Puppet users, and they have encouraged me to take a look. I am having trouble evaluating both choices, though. Chef and Puppet share many of the same domain terminology -- packages, resources, attributes, and so on, and they have a common history that stems from taking different approaches to the same problem. So in some sense they are very similar. But much of the comparison information I've found, like this article, is a little outdated. If you were starting this project today, what questions would you ask yourself to decide whether you should use Chef or Puppet for configuration management? (Note: I don't want answer to the question "Should I use Chef or Puppet?")

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  • What software will tell me if I've already downloaded a video? [closed]

    - by dave
    (I use Linux KNOPPIX (distro 7.0.2, ver 3.3.7) on hard drive.) I download videos of TV programs from the 60s and 70s (mainly from youtube). I copy the youtube URL then paste it into www.keepvid.com to download it (usually .mp4 format). Having now got dozens of such video files (and growing) on my hard drive, I'd like to organise them. WHAT I'D LIKE TO DO IS: Say I find a new vid (of a TV prog) on youtube (or another site), and I'm about to download it. It's possible that I've WATCHED IT BEFORE but have forgotten. So is there software out there that I can run which will do the following: Check for me if I've ALREADY WATCHED the vid that I'm about to download. At the moment, once I've watched a vid on my hard drive, I move the file to another directory called "Watched". But this of course doesn't alert me in the immediate way that I want. . It would crudely suffice, if the software told me AFTER I've downloaded the vid, if I've ALREADY WATCHED it (ie if it's already in my "Watched" directory, or perhaps in a "watched" list). I sometimes alter the filename of the original video file on hard drive, so this might spoil a comparison. If the software alerts me to the fact that I've already watched the vid (preferably BEFORE I download it), then this will allow me to confidently download only new vids that I haven't watched before, and save me duplicating my effort. I'd be most grateful if anyone can suggest such a piece of software, or an alternative solution. I'll be honest, I avoid software that infringes your privacy and control - you know, software that automatically does things behind your back, like upgrades itself over the internet, puts things on your hard drive that you didn't ask for, or sends information from your hard drive to websites.

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  • What guarantees are there on the run-time complexity (Big-O) of LINQ methods?

    - by tzaman
    I've recently started using LINQ quite a bit, and I haven't really seen any mention of run-time complexity for any of the LINQ methods. Obviously, there are many factors at play here, so let's restrict the discussion to the plain IEnumerable LINQ-to-Objects provider. Further, let's assume that any Func passed in as a selector / mutator / etc. is a cheap O(1) operation. It seems obvious that all the single-pass operations (Select, Where, Count, Take/Skip, Any/All, etc.) will be O(n), since they only need to walk the sequence once; although even this is subject to laziness. Things are murkier for the more complex operations; the set-like operators (Union, Distinct, Except, etc.) work using GetHashCode by default (afaik), so it seems reasonable to assume they're using a hash-table internally, making these operations O(n) as well, in general. What about the versions that use an IEqualityComparer? OrderBy would need a sort, so most likely we're looking at O(n log n). What if it's already sorted? How about if I say OrderBy().ThenBy() and provide the same key to both? I could see GroupBy (and Join) using either sorting, or hashing. Which is it? Contains would be O(n) on a List, but O(1) on a HashSet - does LINQ check the underlying container to see if it can speed things up? And the real question - so far, I've been taking it on faith that the operations are performant. However, can I bank on that? STL containers, for example, clearly specify the complexity of every operation. Are there any similar guarantees on LINQ performance in the .NET library specification?

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  • How to find next (by a single parameter) element in c++? (stl) [closed]

    - by user2136963
    I have n humans of THuman class Each human has scored some points in one of two rounds. (score1 and score2) Each human has its unique id. Score1 and 2 are also unique. Besides, a human has a score_t=score1+score2, which can be the same for two of them. I need to implement 6 variables to THuman which return id of a human with: bigger score1 smaller score1 bigger score2 smaller score2 bigger score_t smaller score_t (if there are many humans those satisfy theese conditions, the one with smallest difference of corresponding parameter should be chosen (like score1 for 1 and 2)) In other words, it's some kind of storing 3 human sortings. Two more functions I need should get argument x, set score1 or score 2 to x, and then refresh some of the 6 variables above. If I needed sorting by only one variable, I would simply create set and defined and < operators for my class. But what is the solution for three of parameters? Is it possible to use STL here, or I should create my own lists/treaps? __ Answer: How to update set of pointers c++?

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