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  • How does the bitwise operator '^' work?

    - by SpawnCxy
    I'm a little confused when I see the output of following code: $x = "a"; $y = "b"; $x ^= $y; $y ^= $x; $x ^= $y; echo $x; //got b echo $y; //got a And I wonder how does the operator ^ work here?Explanations with clarity would be greatly appreciated!

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  • Bitwise operations in BC?

    - by user355926
    $ bc BC> ibase=2 BC> 110&101 // wanna get 100 (standar_in) 8: syntax error Wikipedia informs that the ops are "|, & and ^". It may be that they work only in certain BC-types or I misread something.

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  • How to reverse bitwise AND (&) in C ?

    - by VaioIsBorn
    For example i have an operation in C like this: ((unsigned int)ptr & 0xff000000)) The result is bf000000. What do i need at this moment is how to reverse the above i.e. determine the ptr by using the result from the operation and offcourse 0xff000000 . I am asking if there's any simple way to implement this in C, tnx.

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  • YouTube: Tips by Bitwise Courses on NetBeans

    - by Geertjan
    I really like the potential of YouTube in providing a platform for short info clips that take not much time to produce and about as much time to consume. Huw Collingbourne's Bitwise Courses channel is full of exactly this kind of YouTube clip. Several of his YouTube clips are about or make use of NetBeans. The related Twitter account is @bitwisecourses and the homepage is bitwisecourses.com. Here's a great example, the latest YouTube clip created by Bitwise Courses. Very clear and simple explanation, on a specific and narrow topic, and very short and sweet. And very useful! Didn't know about this feature myself. Direct link to the movie: https://www.youtube.com/watch?v=b0fKT_hFQpU Here's to more of these, they're wonderful. More such YouTube clips are needed, short and precise, on very specific topics. And I'm very happy to promote them, as you can see.

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  • How to define 2-bit numbers in C, if possible?

    - by Eddy
    For my university process I'm simulating a process called random sequential adsorption. One of the things I have to do involves randomly depositing squares (which cannot overlap) onto a lattice until there is no more room left, repeating the process several times in order to find the average 'jamming' coverage %. Basically I'm performing operations on a large array of integers, of which 3 possible values exist: 0, 1 and 2. The sites marked with '0' are empty, the sites marked with '1' are full. Initially the array is defined like this: int i, j; int n = 1000000000; int array[n][n]; for(j = 0; j < n; j++) { for(i = 0; i < n; i++) { array[i][j] = 0; } } Say I want to deposit 5*5 squares randomly on the array (that cannot overlap), so that the squares are represented by '1's. This would be done by choosing the x and y coordinates randomly and then creating a 5*5 square of '1's with the topleft point of the square starting at that point. I would then mark sites near the square as '2's. These represent the sites that are unavailable since depositing a square at those sites would cause it to overlap an existing square. This process would continue until there is no more room left to deposit squares on the array (basically, no more '0's left on the array) Anyway, to the point. I would like to make this process as efficient as possible, by using bitwise operations. This would be easy if I didn't have to mark sites near the squares. I was wondering whether creating a 2-bit number would be possible, so that I can account for the sites marked with '2'. Sorry if this sounds really complicated, I just wanted to explain why I want to do this.

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  • cpu floating operations cost

    - by wiso
    I'm interesting in the time cost on a modern desktop cpu of some floating point operations in order to optimize a mathematical evaluation. In particular I'm interested on the comparison between complex operations like exp, log and simple operation like +, *, /. I tried to search for these information, but I can't find a source.

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  • Polynomial operations using operator overloading

    - by Vlad
    I'm trying to use operator overloading to define the basic operations (+,-,*,/) for my polynomial class but when i run the program it crashes and my computer frozes. Update3 Ok i successfully done the first two operations(+,-). Now at multiplication, after multiplying each term of the first polynomial with each of the second i want to sort the poly list descending and then if there are more than one term with the same power to merge them in only one term, but for some reason it doesn't compile because of the sort function which doesn't work. Here's what I got: polinom operator*(const polinom& P) const { polinom Result; constIter i, j, lastItem = Result.poly.end(); Iter it1, it2; int nr_matches; for (i = poly.begin() ; i != poly.end(); i++) { for (j = P.poly.begin(); j != P.poly.end(); j++) Result.insert(i->coef * j->coef, i->pow + j->pow); } sort(Result.poly.begin(), Result.poly.end(), SortDescending()); lastItem--; while (true) { nr_matches = 0; for (it1 = Result.poly.begin(); it < lastItem; it1++) { for (it2 = it1 + 1;; it2 <= lastItem; it2++){ if (it2->pow == it1->pow) { it1->coef += it2->coef; nr_matches++; } } Result.poly.erase(it1 + 1, it1 + (nr_matches + 1)); } return Result; } Also here's SortDescending: struct SortDescending { bool operator()(const term& t1, const term& t2) { return t2.pow < t1.pow; } }; What did i do wrong? Thanks!

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  • One position right barrel shift using ALU Operators?

    - by Tomek
    I was wondering if there was an efficient way to perform a shift right on an 8 bit binary value using only ALU Operators (NOT, OR, AND, XOR, ADD, SUB) Example: input: 00110101 output: 10011010 I have been able to implement a shift left by just adding the 8 bit binary value with itself since a shift left is equivalent to multiplying by 2. However, I can't think of a way to do this for shift right. The only method I have come up with so far is to just perform 7 left barrel shifts. Is this the only way?

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  • Java print binary number using bit-wise operator

    - by user69514
    Hi I am creating a method that will take a number and print it along with its binary representation. The problems is that my method prints all 0's for any positive number, and all 1's for any negative number private static void display( int number ){ System.out.print(number + "\t"); int mask = 1 << 31; for(int i=1; i<=32; i++) { if( (mask & number) != 0 ) System.out.print(1); else System.out.print(0); if( (i % 4) == 0 ) System.out.print(" "); } }

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  • Override default operations order in LINQ

    - by Erick
    For one of our applications we do use LINQ to update a few reccords of the database. For business reasons we do require that only one item of a list to be primary. When we designed we decided to fire all of queries at the database at once. The problems occurs when we add one row and update the primary element to be the second item. See, the default behavior for order of operations with LINQ is to Insert, Update, Delete. If I Insert a first element I get a check constraint error with SQL Server. The best in my opinion would be to override and make sure to Update before Insert, this way we make sure that check constraints are kept. Tho there is not a lot of documentation on the mather. Any idea ?

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  • Which are the fundamental stack manipulation operations?

    - by Aadit M Shah
    I'm creating a stack oriented virtual machine, and so I started learning Forth for a general understanding about how it would work. Then I shortlisted the essential stack manipulation operations I would need to implement in my virtual machine: drop ( a -- ) dup ( a -- a a ) swap ( a b -- b a ) rot ( a b c -- b c a ) I believe that the following four stack manipulation operations can be used to simulate any other stack manipulation operation. For example: nip ( a b -- b ) swap drop -rot ( a b c -- c a b ) rot rot tuck ( a b -- b a b ) dup -rot over ( a b -- a b a ) swap tuck That being said however I wanted to know whether I have listed all the fundamental stack manipulation operations necessary to manipulate the stack in any possible way. Are there any more fundamental stack manipulation operations I would need to implement, without which my virtual machine wouldn't be Turing complete?

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  • Bitwise operators in DX9 ps_2_0 shader

    - by lapin
    I've got the following code in a shader: // v & y are both floats nPixel = v; nPixel << 8; nPixel |= y; and this gives me the following error in compilation: shader.fx(80,10): error X3535: Bitwise operations not supported on legacy targets. shader.fx(92,18): ID3DXEffectCompiler::CompileEffect: There was an error compiling expression ID3DXEffectCompiler: Compilation failed The error is on the following line: nPixel |= y; What am I doing wrong here?

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  • Ouya / Android : button mapping bitwise

    - by scorvi
    I am programming a game with the Gameplay3d Engine. But the Android site has no gamepad support and that is what I need to port my game to Ouya. So I implemented a simple gamepad support and it supports 2 gamepads. So my problem is that I put the button stats in a float array for every gamepad. But the Gameplay3d engine saves their stats in a unsigned int _buttons variable. It is set with bitwise operations and I have no clue how to translate my array to this.

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  • Turn O&M Operations into Optimized Projects with Oracle Primavera

    - by mark.kromer
    Oracle enterprise project portfolio management with Primavera is much more than optimizing project performance and eliminating project failure on new projects, capital programs, etc. A very common use case that we see is small-scale frequent and recurring projects based on on-going operations and maintenance. As opposed to assigning resources to various activities when you are building a new network infrastructure, for example, Oracle has teamed-up the Primavera and eBusiness Suite teams to provide direct integration for work orders from Oracle's Enterprise Asset Management (eAM) system to populate into Primavera P6 project schedules. So now that your network infrastructure build-out project is complete, planners and operations managers can use the world-class what-if and scheduling capabilities in Primavera tools to assign work orders, maximize resource utilization and to reuse templates for typical O&M operations in Primavera and share that back to the operations teams using eAM for maintenance. Also, large-scale maintenance operations related to large assets in the asset lifecycle will include phase-outs, shutdowns and turn-arounds which are classic maintenance projects, as opposed to building something new, that Oracle Primavera with Oracle e-Business Suite provides full coverage to optimize your ALM processes in your business. Read more about these new capabilities from Oracle in the ERP space from the Oracle eAM data sheet.

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  • Nested multithread operations tracing

    - by Sinix
    I've a code alike void ExecuteTraced(Action a, string message) { TraceOpStart(message); a(); TraceOpEnd(message); } The callback (a) could call ExecuteTraced again, and, in some cases, asynchronously (via ThreadPool, BeginInvoke, PLINQ etc, so I've no ability to explicitly mark operation scope). I want to trace all operation nested (even if they perform asynchronously). So, I need the ability to get last traced operation inside logical call context (there may be a lot of concurrent threads, so it's impossible to use lastTraced static field). There're CallContext.LogicalGetData and CallContext.LogicalSetData, but unfortunately, LogicalCallContext propagates changes back to the parent context as EndInvoke() called. Even worse, this may occure at any moment if EndInvoke() was called async. http://stackoverflow.com/questions/883486/endinvoke-changes-current-callcontext-why Also, there is Trace.CorrelationManager, but it based on CallContext and have all the same troubles. There's a workaround: use the CallContext.HostContext property which does not propagates back as async operation ended. Also, it does'nt clone, so the value should be immutable - not a problem. Though, it's used by HttpContext and so, workaround is not usable in Asp.Net apps. The only way I see is to wrap HostContext (if not mine) or entire LogicalCallContext into dynamic and dispatch all calls beside last traced operation. Help, please!

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  • ASP.net file operations delay

    - by mtranda
    Ok, so here's the problem: I'm reading the stream from a FileUpload control, reading in chunks of n bytes and writing the array in a loop until I reach the stream's end. Now the reason I do this is because I need to check several things while the upload is still going on (rather than doing a Save(); which does the whole thing in one go). Here's the problem: when doing this from the local machine, I can see the file just fine as it's uploading and its size increases (had to add a Sleep(); clause in the loop to actually get to see the file being written). However, when I upload the file from a remote machine, I don't get to see it until the the file has completed uploading. Also, I've added another call to write the progress to a text file as the progress is going on, and I get the same thing. Local: the file updates as the upload goes on, remote: the token file only appears after the upload's done (which is somewhat useless since I need it while the upload's still happening). Is there some sort of security setting in (or ASP.net) that maybe saves files in a temporary location for remote machines as opposed to the local machine and then moves them to the specified destination? I would liken this with ASP.net displaying error messages when browsing from the local machine (even on the public hostname) as opposed to the generic compilation error page/generic exception page that is shown when browsing from a remote machine (and customErrors are not off) Any clues on this? Thanks in advance.

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  • c - difficulties with bit operations

    - by hatorade
    I'm debugging a program with GDB. unsigned int example = ~0; gives me: (gdb) x/4bt example 0xffd99788: 10101000 10010111 11011001 11111111 why is this not all 1's? i defined it as ~0... then the next line of code is: example>>=(31); and GDB gives me this when I try to examine the memory at bits: (gdb) x/4bt example 0xffffffff: Cannot access memory at address 0xffffffff what is going on???

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  • Asynchronous SQL Operations

    - by Paul Hatcherian
    I've got a problem I'm not sure how best to solve. I have an application which updates a database in response to ad hoc requests. One request in particular is quite common. The request is an update that by itself is quite simple, but has some complex preconditions. For this request the business layer first requests a set of data from the data layer. The business logic layer evaluated the data from the database and parameters from the request, from this the action to be performed is determined, and the request's response message(s) are created. The business layer now executes the actual update command that is the purpose of the request. This last step is the problem, this command is dependent on the state of the database, which might have changed since the business logic ran. Locking down the data read in this operation across several round-trips to the database doesn't seem like a good idea either. Is there a 'best-practice' way to accomplish something like this? Thanks!

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  • Implementing set operations in TSQL

    - by dotneteer
    SQL excels at operating on dataset. In this post, I will discuss how to implement basic set operations in transact SQL (TSQL). The operations that I am going to discuss are union, intersection and complement (subtraction).   Union Intersection Complement (subtraction) Implementing set operations using union, intersect and except We can use TSQL keywords union, intersect and except to implement set operations. Since we are in an election year, I will use voter records of propositions as an example. We create the following table and insert 6 records into the table. declare @votes table (VoterId int, PropId int) insert into @votes values (1, 30) insert into @votes values (2, 30) insert into @votes values (3, 30) insert into @votes values (4, 30) insert into @votes values (4, 31) insert into @votes values (5, 31) Voters 1, 2, 3 and 4 voted for proposition 30 and voters 4 and 5 voted for proposition 31. The following TSQL statement implements union using the union keyword. The union returns voters who voted for either proposition 30 or 31. select VoterId from @votes where PropId = 30 union select VoterId from @votes where PropId = 31 The following TSQL statement implements intersection using the intersect keyword. The intersection will return voters who voted only for both proposition 30 and 31. select VoterId from @votes where PropId = 30 intersect select VoterId from @votes where PropId = 31 The following TSQL statement implements complement using the except keyword. The complement will return voters who voted for proposition 30 but not 31. select VoterId from @votes where PropId = 30 except select VoterId from @votes where PropId = 31 Implementing set operations using join An alternative way to implement set operation in TSQL is to use full outer join, inner join and left outer join. The following TSQL statement implements union using full outer join. select Coalesce(A.VoterId, B.VoterId) from (select VoterId from @votes where PropId = 30) A full outer join (select VoterId from @votes where PropId = 31) B on A.VoterId = B.VoterId The following TSQL statement implements intersection using inner join. select Coalesce(A.VoterId, B.VoterId) from (select VoterId from @votes where PropId = 30) A inner join (select VoterId from @votes where PropId = 31) B on A.VoterId = B.VoterId The following TSQL statement implements complement using left outer join. select Coalesce(A.VoterId, B.VoterId) from (select VoterId from @votes where PropId = 30) A left outer join (select VoterId from @votes where PropId = 31) B on A.VoterId = B.VoterId where B.VoterId is null Which one to choose? To choose which technique to use, just keep two things in mind: The union, intersect and except technique treats an entire record as a member. The join technique allows the member to be specified in the “on” clause. However, it is necessary to use Coalesce function to project sets on the two sides of the join into a single set.

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  • SQL SERVER – Merge Operations – Insert, Update, Delete in Single Execution

    - by pinaldave
    This blog post is written in response to T-SQL Tuesday hosted by Jorge Segarra (aka SQLChicken). I have been very active using these Merge operations in my development. However, I have found out from my consultancy work and friends that these amazing operations are not utilized by them most of the time. Here is my attempt to bring the necessity of using the Merge Operation to surface one more time. MERGE is a new feature that provides an efficient way to do multiple DML operations. In earlier versions of SQL Server, we had to write separate statements to INSERT, UPDATE, or DELETE data based on certain conditions; however, at present, by using the MERGE statement, we can include the logic of such data changes in one statement that even checks when the data is matched and then just update it, and similarly, when the data is unmatched, it is inserted. One of the most important advantages of MERGE statement is that the entire data are read and processed only once. In earlier versions, three different statements had to be written to process three different activities (INSERT, UPDATE or DELETE); however, by using MERGE statement, all the update activities can be done in one pass of database table. I have written about these Merge Operations earlier in my blog post over here SQL SERVER – 2008 – Introduction to Merge Statement – One Statement for INSERT, UPDATE, DELETE. I was asked by one of the readers that how do we know that this operator was doing everything in single pass and was not calling this Merge Operator multiple times. Let us run the same example which I have used earlier; I am listing the same here again for convenience. --Let’s create Student Details and StudentTotalMarks and inserted some records. USE tempdb GO CREATE TABLE StudentDetails ( StudentID INTEGER PRIMARY KEY, StudentName VARCHAR(15) ) GO INSERT INTO StudentDetails VALUES(1,'SMITH') INSERT INTO StudentDetails VALUES(2,'ALLEN') INSERT INTO StudentDetails VALUES(3,'JONES') INSERT INTO StudentDetails VALUES(4,'MARTIN') INSERT INTO StudentDetails VALUES(5,'JAMES') GO CREATE TABLE StudentTotalMarks ( StudentID INTEGER REFERENCES StudentDetails, StudentMarks INTEGER ) GO INSERT INTO StudentTotalMarks VALUES(1,230) INSERT INTO StudentTotalMarks VALUES(2,255) INSERT INTO StudentTotalMarks VALUES(3,200) GO -- Select from Table SELECT * FROM StudentDetails GO SELECT * FROM StudentTotalMarks GO -- Merge Statement MERGE StudentTotalMarks AS stm USING (SELECT StudentID,StudentName FROM StudentDetails) AS sd ON stm.StudentID = sd.StudentID WHEN MATCHED AND stm.StudentMarks > 250 THEN DELETE WHEN MATCHED THEN UPDATE SET stm.StudentMarks = stm.StudentMarks + 25 WHEN NOT MATCHED THEN INSERT(StudentID,StudentMarks) VALUES(sd.StudentID,25); GO -- Select from Table SELECT * FROM StudentDetails GO SELECT * FROM StudentTotalMarks GO -- Clean up DROP TABLE StudentDetails GO DROP TABLE StudentTotalMarks GO The Merge Join performs very well and the following result is obtained. Let us check the execution plan for the merge operator. You can click on following image to enlarge it. Let us evaluate the execution plan for the Table Merge Operator only. We can clearly see that the Number of Executions property suggests value 1. Which is quite clear that in a single PASS, the Merge Operation completes the operations of Insert, Update and Delete. I strongly suggest you all to use this operation, if possible, in your development. I have seen this operation implemented in many data warehousing applications. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Joins, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Merge

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  • Minimal set of critical database operations

    - by Juan Carlos Coto
    In designing the data layer code for an application, I'm trying to determine if there is a minimal set of database operations (both single and combined) that are essential for proper application function (i.e. the database is left in an expected state after every data access call). Is there a way to determine the minimal set of database operations (functions, transactions, etc.) that are critical for an application to function correctly? How do I find it? Thanks very much!

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  • Changing the Game: Why Oracle is in the IT Operations Management Business

    - by DanKoloski
    v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} Next week, in Orlando, is the annual Gartner IT Operations Management Summit. Oracle is a premier sponsor of this annual event, which brings together IT executives for several days of high level talks about the state of operational management of enterprise IT. This year, Sushil Kumar, VP Product Strategy and Business Development for Oracle’s Systems & Applications Management, will be presenting on the transformation in IT Operations required to support enterprise cloud computing. IT Operations transformation is an important subject, because year after year, we hear essentially the same refrain – large enterprises spend an average of two-thirds (67%!) of their IT resources (budget, energy, time, people, etc.) on running the business, with far too little left over to spend on growing and transforming the business (which is what the business actually needs and wants). In the thirtieth year of the distributed computing revolution (give or take, depending on how you count it), it’s amazing that we have still not moved the needle on the single biggest component of enterprise IT resource utilization. Oracle is in the IT Operations Management business because when management is engineered together with the technology under management, the resulting efficiency gains can be truly staggering. To put it simply – what if you could turn that 67% of IT resources spent on running the business into 50%? Or 40%? Imagine what you could do with those resources. It’s now not just possible, but happening. This seems like a simple idea, but it is a radical change from “business as usual” in enterprise IT Operations. For the last thirty years, management has been a bolted-on afterthought – we pick and deploy our technology, then figure out how to manage it. This pervasive dysfunction is a broken cycle that guarantees high ongoing operating costs and low agility. If we want to break the cycle, we need to take a more tightly-coupled approach. As a complete applications-to-disk platform provider, Oracle is engineering management together with technology across our stack and hooking that on-premise management up live to My Oracle Support. Let’s examine the results with just one piece of the Oracle stack – the Oracle Database. Oracle began this journey with the Oracle Database 9i many years ago with the introduction of low-impact instrumentation in the database kernel (“tell me what’s wrong”) and through Database 10g, 11g and 11gR2 has successively added integrated advisory (“tell me how to fix what’s wrong”) and lifecycle management and automated self-tuning (“fix it for me, and do it on an ongoing basis for all my assets”). When enterprises take advantage of this tight-coupling, the results are game-changing. Consider the following (for a full list of public references, visit this link): British Telecom improved database provisioning time 1000% (from weeks to minutes) which allows them to provide a new DBaaS service to their internal customers with no additional resources Cerner Corporation Saved $9.5 million in CapEx and OpEx AND launched a brand-new cloud business at the same time Vodafone Group plc improved response times 50% and reduced maintenance planning times 50-60% while serving 391 million registered mobile customers Or the recent Database Manageability and Productivity Cost Comparisons: Oracle Database 11g Release 2 vs. SAP Sybase ASE 15.7, Microsoft SQL Server 2008 R2 and IBM DB2 9.7 as conducted by independent analyst firm ORC. In later entries, we’ll discuss similar results across other portions of the Oracle stack and how these efficiency gains are required to achieve the agility benefits of Enterprise Cloud. Stay Connected: Twitter |  Face book |  You Tube |  Linked in |  Newsletter

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