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Search found 1100 results on 44 pages for 'bitwise operators'.

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  • What does "===" mean?

    - by Stefan Konno
    I recently studied some code that I'm supposed to use for different reasons, it's unrelevant. The thing I've noticed is someone using the operator "===" which I can't make sense out of. I've tried it with a function and it corresponds in crazy ways. The language is PHP by the way. Does anyone know what the definition of this operator is, I can't even find it in the declaration of php operators.

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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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  • 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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  • Conversion constructor vs. conversion operator: precedence

    - by GRB
    Reading some questions here on SO about conversion operators and constructors got me thinking about the interaction between them, namely when there is an 'ambiguous' call. Consider the following code: class A; class B { public: B(){} B(const A&) //conversion constructor { cout << "called B's conversion constructor" << endl; } }; class A { public: operator B() //conversion operator { cout << "called A's conversion operator" << endl; return B(); } }; int main() { B b = A(); //what should be called here? apparently, A::operator B() return 0; } The above code displays "called A's conversion operator", meaning that the conversion operator is called as opposed to the constructor. If you remove/comment out the operator B() code from A, the compiler will happily switch over to using the constructor instead (with no other changes to the code). My questions are: Since the compiler doesn't consider B b = A(); to be an ambiguous call, there must be some type of precedence at work here. Where exactly is this precedence established? (a reference/quote from the C++ standard would be appreciated) From an object-oriented philosophical standpoint, is this the way the code should behave? Who knows more about how an A object should become a B object, A or B? According to C++, the answer is A -- is there anything in object-oriented practice that suggests this should be the case? To me personally, it would make sense either way, so I'm interested to know how the choice was made. Thanks in advance

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  • The EXCEPT and INTERSECT Operators in SQL Server

    The UNION, EXCEPT and INTERSECT operators of SQL enable you to combine more than one SELECT statement to form a single result set. Rob Sheldon explains all, with plenty of examples. Join SQL Backup’s 35,000+ customers to compress and strengthen your backups "SQL Backup will be a REAL boost to any DBA lucky enough to use it." Jonathan Allen. Download a free trial now.

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  • Bringing Alerts and Operators together with Notifications

    - by fatherjack
    I have covered SQL Server Alerts (Alerts are good, arent they?) on this blog before and I more recently did a post regarding Notifications (Are your Jobs talking to you) and how they should be configured. Now we need to check that these things are linked up so that when an Alert condition is met that you get the appropriate Notifications sent to Operators. Straight into the code we need and then a review of what it does ... DECLARE @ChosenOperator SYSNAME DECLARE @FailSafeOp TABLE ...(read more)

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  • What is the justification for Python's power operator associating to the right?

    - by Pieter Müller
    I am writing code to parse mathematical expression strings, and noticed that the order in which chained power operators are evaluated in Python differs from the order in Excel. From http://docs.python.org/reference/expressions.html: "Thus, in an unparenthesized sequence of power and unary operators, the operators are evaluated from right to left (this does not constrain the evaluation order for the operands): -1*2 results in -1."* This means that, in Python: 2**2**3 is evaluated as 2**(2**3) = 2**8 = 256 In Excel, it works the other way around: 2^2^3 is evaluated as (2^2)^3 = 4^3 = 64 I now have to choose an implementation for my own parser. The Excel order is easier to implement, as it mirrors the evaluation order of multiplication. I asked some people around the office what their gut feel was for the evaluation of 2^2^3 and got mixed responses. Does anybody know of any good reasons or conciderations in favour of the Python implementation? And if you don't have an answer, please comment with the result you get from gut feel - 64 or 256?

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  • Arguments for or against using Try/Catch as logical operators

    - by James P. Wright
    I just discovered some lovely code in our companies app that uses Try-Catch blocks as logical operators. Meaning, "do some code, if that throws this error, do this code, but if that throws this error do this 3rd thing instead". It uses "Finally" as the "else" statement it appears. I know that this is wrong inherently, but before I go picking a fight I was hoping for some well thought out arguments. And hey, if you have arguments FOR the use of Try-Catch in this manner, please do tell. EDIT For any who are wondering, the language is C# and the code in question is about 30+ lines and is looking for specific exceptions, it is not handling ALL exceptions.

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  • Implementing comparision operators via 'tuple' and 'tie', a good idea?

    - by Xeo
    (Note: tuple and tie can be taken from Boost or C++11.) When writing small structs with only two elements, I sometimes tend to choose a std::pair, as all important stuff is already done for that datatype, like operator< for strict-weak-ordering. The downsides though are the pretty much useless variable names. Even if I myself created that typedef, I won't remember 2 days later what first and what second exactly was, especially if they are both of the same type. This gets even worse for more than two members, as nesting pairs pretty much sucks. The other option for that is a tuple, either from Boost or C++11, but that doesn't really look any nicer and clearer. So I go back to writing the structs myself, including any needed comparision operators. Since especially the operator< can be quite cumbersome, I thought of circumventing this whole mess by just relying on the operations defined for tuple: Example of operator<, e.g. for strict-weak-ordering: bool operator<(MyStruct const& lhs, MyStruct const& rhs){ return std::tie(lhs.one_member, lhs.another, lhs.yet_more) < std::tie(rhs.one_member, rhs.another, rhs.yet_more); } (tie makes a tuple of T& references from the passed arguments.) Edit: The suggestion from @DeadMG to privately inherit from tuple isn't a bad one, but it got quite some drawbacks: If the operators are free-standing (possibly friends), I need to inherit publicly With casting, my functions / operators (operator= specifically) can be easily bypassed With the tie solution, I can leave out certain members if they don't matter for the ordering Are there any drawbacks in this implementation that I need to consider?

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  • What are these values representative of in C bitwise operations?

    - by ajax81
    Hi All, I'm trying to reverse the order of bits in C (homework question, subject: bitwise operators). I found this solution, but I'm a little confused by the hex values (?) used -- 0x01 and 0x80. unsigned char reverse(unsigned char c) { int shift; unsigned char result = 0; for (shift = 0; shift < CHAR_BITS; shift++) { if (c & (0x01 << shift)) result |= (0x80 >> shift); } return result; } The book I'm working out of hasn't discussed these kinds of values, so I'm not really sure what to make of them. Can somebody shed some light on this solution? Thank you!

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  • Working with Reporting Services Filters – Part 3: The TOP and BOTTOM Operators

    - by smisner
    Thus far in this series, I have described using the IN operator and the LIKE operator. Today, I’ll continue the series by reviewing the TOP and BOTTOM operators. Today, I happened to be working on an example of using the TOP N operator and was not successful on my first try because the behavior is just a bit different than we find when using an “equals” comparison as I described in my first post in this series. In my example, I wanted to display a list of the top 5 resellers in the United States for AdventureWorks, but I wanted it based on a filter. I started with a hard-coded filter like this: Expression Data Type Operator Value [ResellerSalesAmount] Float Top N 5 And received the following error: A filter value in the filter for tablix 'Tablix1' specifies a data type that is not supported by the 'TopN' operator. Verify that the data type for each filter value is Integer. Well, that puzzled me. Did I really have to convert ResellerSalesAmount to an integer to use the Top N operator? Just for kicks, I switched to the Top % operator like this: Expression Data Type Operator Value [ResellerSalesAmount] Float Top % 50 This time, I got exactly the results I expected – I had a total of 10 records in my dataset results, so 50% of that should yield 5 rows in my tablix. So thinking about the problem with Top N some  more, I switched the Value to an expression, like this: Expression Data Type Operator Value [ResellerSalesAmount] Float Top N =5 And it worked! So the value for Top N or Top % must reflect a number to plug into the calculation, such as Top 5 or Top 50%, and the expression is the basis for determining what’s in that group. In other words, Reporting Services will sort the rows by the expression – ResellerSalesAmount in this case – in descending order, and then filter out everything except the topmost rows based on the operator you specify. The curious thing is that, if you’re going to hard-code the value, you must enter the value for Top N with an equal sign in front of the integer, but you can omit the equal sign when entering a hard-coded value for Top %. This experience is why working with Reporting Services filters is not always intuitive! When you use a report parameter to set the value, you won’t have this problem. Just be sure that the data type of the report parameter is set to Integer. Jessica Moss has an example of using a Top N filter in a tablix which you can view here. Working with Bottom N and Bottom % works similarly. You just provide a number for N or for the percentage and Reporting Services works from the bottom up to determine which rows are kept and which are excluded.

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