Search Results

Search found 34668 results on 1387 pages for 'return'.

Page 8/1387 | < Previous Page | 4 5 6 7 8 9 10 11 12 13 14 15  | Next Page >

  • Partial template specialization for more than one typename

    - by Matt Joiner
    In the following code, I want to consider functions (Ops) that have void return to instead be considered to return true. The type Retval, and the return value of Op are always matching. I'm not able to discriminate using the type traits shown here, and attempts to create a partial template specialization based on Retval have failed due the presence of the other template variables, Op and Args. How do I specialize only some variables in a template specialization without getting errors? Is there any other way to alter behaviour based on the return type of Op? template <typename Retval, typename Op, typename... Args> Retval single_op_wrapper( Retval const failval, char const *const opname, Op const op, Cpfs &cpfs, Args... args) { try { CallContext callctx(cpfs, opname); Retval retval; if (std::is_same<bool, Retval>::value) { (callctx.*op)(args...); retval = true; } else { retval = (callctx.*op)(args...); } assert(retval != failval); callctx.commit(cpfs); return retval; } catch (CpfsError const &exc) { cpfs_errno_set(exc.fserrno); LOGF(Info, "Failed with %s", cpfs_errno_str(exc.fserrno)); } return failval; }

    Read the article

  • Java generic return type

    - by Colby77
    Hi, I'd like to write a method that can accept a type param (or whatever the method can figure out the type from) and return a value of this type so I don't have to cast the return type. Here is a method: public Object doIt(Object param){ if(param instanceof String){ return "string"; }else if(param instanceof Integer){ return 1; }else{ return null; } } When I call this method, and pass in it a String, even if I know the return type will be a String I have to cast the return Object. This is similar to the int param. How shall I write this method to accept a type param, and return this type?

    Read the article

  • Java generic return tpye

    - by Colby77
    Hi, I'd like to write a method that can accept a type param (or whatever the method can figure out the type from) and return a value of this type so I don't have to cast the return type. Here is a method: public Object doIt(Object param){ if(param instanceof String){ return "string"; }else if(param instanceof Integer){ return 1; }else{ return null; } } When I call this method, and pass in it a String, even if I know the return type will be a String I have to cast the return Object. This is similar to the int param. How shall I write this method to accept a type param, and return this type?

    Read the article

  • Which style of return is "better" for a method that might return None?

    - by Daenyth
    I have a method that will either return an object or None if the lookup fails. Which style of the following is better? def get_foo(needle): haystack = object_dict() if needle not in haystack: return None return haystack[needle] or, def get_foo(needle): haystack = object_dict() try: return haystack[needle] except KeyError: # Needle not found return None I'm undecided as to which is more more desirable myself. Another choice would be return haystack[needle] if needle in haystack else None, but I'm not sure that's any better.

    Read the article

  • How to implement early exit / return in Haskell?

    - by Giorgio
    I am porting a Java application to Haskell. The main method of the Java application follows the pattern: public static void main(String [] args) { if (args.length == 0) { System.out.println("Invalid number of arguments."); System.exit(1); } SomeDataType d = getData(arg[0]); if (!dataOk(d)) { System.out.println("Could not read input data."); System.exit(1); } SomeDataType r = processData(d); if (!resultOk(r)) { System.out.println("Processing failed."); System.exit(1); } ... } So I have different steps and after each step I can either exit with an error code, or continue to the following step. My attempt at porting this to Haskell goes as follows: main :: IO () main = do a <- getArgs if ((length args) == 0) then do putStrLn "Invalid number of arguments." exitWith (ExitFailure 1) else do -- The rest of the main function goes here. With this solution, I will have lots of nested if-then-else (one for each exit point of the original Java code). Is there a more elegant / idiomatic way of implementing this pattern in Haskell? In general, what is a Haskell idiomatic way to implement an early exit / return as used in an imperative language like Java?

    Read the article

  • The Return Of __FILE__ And __LINE__ In .NET 4.5

    - by Alois Kraus
    Good things are hard to kill. One of the most useful predefined compiler macros in C/C++ were __FILE__ and __LINE__ which do expand to the compilation units file name and line number where this value is encountered by the compiler. After 4.5 versions of .NET we are on par with C/C++ again. It is of course not a simple compiler expandable macro it is an attribute but it does serve exactly the same purpose. Now we do get CallerLineNumberAttribute  == __LINE__ CallerFilePathAttribute        == __FILE__ CallerMemberNameAttribute  == __FUNCTION__ (MSVC Extension)   The most important one is CallerMemberNameAttribute which is very useful to implement the INotifyPropertyChanged interface without the need to hard code the name of the property anymore. Now you can simply decorate your change method with the new CallerMemberName attribute and you get the property name as string directly inserted by the C# compiler at compile time.   public string UserName { get { return _userName; } set { _userName=value; RaisePropertyChanged(); // no more RaisePropertyChanged(“UserName”)! } } protected void RaisePropertyChanged([CallerMemberName] string member = "") { var copy = PropertyChanged; if(copy != null) { copy(new PropertyChangedEventArgs(this, member)); } } Nice and handy. This was obviously the prime reason to implement this feature in the C# 5.0 compiler. You can repurpose this feature for tracing to get your hands on the method name of your caller along other stuff very fast now. All infos are added during compile time which is much faster than other approaches like walking the stack. The example on MSDN shows the usage of this attribute with an example public static void TraceMessage(string message, [CallerMemberName] string memberName = "", [CallerFilePath] string sourceFilePath = "", [CallerLineNumber] int sourceLineNumber = 0) { Console.WriteLine("Hi {0} {1} {2}({3})", message, memberName, sourceFilePath, sourceLineNumber); }   When I do think of tracing I do usually want to have a API which allows me to Trace method enter and leave Trace messages with a severity like Info, Warning, Error When I do print a trace message it is very useful to print out method and type name as well. So your API must either be able to pass the method and type name as strings or extract it automatically via walking back one Stackframe and fetch the infos from there. The first glaring deficiency is that there is no CallerTypeAttribute yet because the C# compiler team was not satisfied with its performance.   A usable Trace Api might therefore look like   enum TraceTypes { None = 0, EnterLeave = 1 << 0, Info = 1 << 1, Warn = 1 << 2, Error = 1 << 3 } class Tracer : IDisposable { string Type; string Method; public Tracer(string type, string method) { Type = type; Method = method; if (IsEnabled(TraceTypes.EnterLeave,Type, Method)) { } } private bool IsEnabled(TraceTypes traceTypes, string Type, string Method) { // Do checking here if tracing is enabled return false; } public void Info(string fmt, params object[] args) { } public void Warn(string fmt, params object[] args) { } public void Error(string fmt, params object[] args) { } public static void Info(string type, string method, string fmt, params object[] args) { } public static void Warn(string type, string method, string fmt, params object[] args) { } public static void Error(string type, string method, string fmt, params object[] args) { } public void Dispose() { // trace method leave } } This minimal trace API is very fast but hard to maintain since you need to pass in the type and method name as hard coded strings which can change from time to time. But now we have at least CallerMemberName to rid of the explicit method parameter right? Not really. Since any acceptable usable trace Api should have a method signature like Tracexxx(… string fmt, params [] object args) we not able to add additional optional parameters after the args array. If we would put it before the format string we would need to make it optional as well which would mean the compiler would need to figure out what our trace message and arguments are (not likely) or we would need to specify everything explicitly just like before . There are ways around this by providing a myriad of overloads which in the end are routed to the very same method but that is ugly. I am not sure if nobody inside MS agrees that the above API is reasonable to have or (more likely) that the whole talk about you can use this feature for diagnostic purposes was not a core feature at all but a simple byproduct of making the life of INotifyPropertyChanged implementers easier. A way around this would be to allow for variable argument arrays after the params keyword another set of optional arguments which are always filled by the compiler but I do not know if this is an easy one. The thing I am missing much more is the not provided CallerType attribute. But not in the way you would think of. In the API above I did add some filtering based on method and type to stay as fast as possible for types where tracing is not enabled at all. It should be no more expensive than an additional method call and a bool variable check if tracing for this type is enabled at all. The data is tightly bound to the calling type and method and should therefore become part of the static type instance. Since extending the CLR type system for tracing is not something I do expect to happen I have come up with an alternative approach which allows me basically to attach run time data to any existing type object in super fast way. The key to success is the usage of generics.   class Tracer<T> : IDisposable { string Method; public Tracer(string method) { if (TraceData<T>.Instance.Enabled.HasFlag(TraceTypes.EnterLeave)) { } } public void Dispose() { if (TraceData<T>.Instance.Enabled.HasFlag(TraceTypes.EnterLeave)) { } } public static void Info(string fmt, params object[] args) { } /// <summary> /// Every type gets its own instance with a fresh set of variables to describe the /// current filter status. /// </summary> /// <typeparam name="T"></typeparam> internal class TraceData<UsingType> { internal static TraceData<UsingType> Instance = new TraceData<UsingType>(); public bool IsInitialized = false; // flag if we need to reinit the trace data in case of reconfigured trace settings at runtime public TraceTypes Enabled = TraceTypes.None; // Enabled trace levels for this type } } We do not need to pass the type as string or Type object to the trace Api. Instead we define a generic Api that accepts the using type as generic parameter. Then we can create a TraceData static instance which is due to the nature of generics a fresh instance for every new type parameter. My tests on my home machine have shown that this approach is as fast as a simple bool flag check. If you have an application with many types using tracing you do not want to bring the app down by simply enabling tracing for one special rarely used type. The trace filter performance for the types which are not enabled must be therefore the fasted code path. This approach has the nice side effect that if you store the TraceData instances in one global list you can reconfigure tracing at runtime safely by simply setting the IsInitialized flag to false. A similar effect can be achieved with a global static Dictionary<Type,TraceData> object but big hash tables have random memory access semantics which is bad for cache locality and you always need to pay for the lookup which involves hash code generation, equality check and an indexed array access. The generic version is wicked fast and allows you to add more features to your tracing Api with minimal perf overhead. But it is cumbersome to write the generic type argument always explicitly and worse if you do refactor code and move parts of it to other classes it might be that you cannot configure tracing correctly. I would like therefore to decorate my type with an attribute [CallerType] class Tracer<T> : IDisposable to tell the compiler to fill in the generic type argument automatically. class Program { static void Main(string[] args) { using (var t = new Tracer()) // equivalent to new Tracer<Program>() { That would be really useful and super fast since you do not need to pass any type object around but you do have full type infos at hand. This change would be breaking if another non generic type exists in the same namespace where now the generic counterpart would be preferred. But this is an acceptable risk in my opinion since you can today already get conflicts if two generic types of the same name are defined in different namespaces. This would be only a variation of this issue. When you do think about this further you can add more features like to trace the exception in your Dispose method if the method is left with an exception with that little trick I did write some time ago. You can think of tracing as a super fast and configurable switch to write data to an output destination or to execute alternative actions. With such an infrastructure you can e.g. Reconfigure tracing at run time. Take a memory dump when a specific method is left with a specific exception. Throw an exception when a specific trace statement is hit (useful for testing error conditions). Execute a passed delegate which e.g. dumps additional state when enabled. Write data to an in memory ring buffer and dump it when specific events do occur (e.g. method is left with an exception, triggered from outside). Write data to an output device. …. This stuff is really useful to have when your code is in production on a mission critical server and you need to find the root cause of sporadic crashes of your application. It could be a buggy graphics card driver which throws access violations into your application (ok with .NET 4 not anymore except if you enable a compatibility flag) where you would like to have a minidump or you have reached after two weeks of operation a state where you need a full memory dump at a specific point in time in the middle of an transaction. At my older machine I do get with this super fast approach 50 million traces/s when tracing is disabled. When I do know that tracing is enabled for this type I can walk the stack by using StackFrameHelper.GetStackFramesInternal to check further if a specific action or output device is configured for this method which is about 2-3 times faster than the regular StackTrace class. Even with one String.Format I am down to 3 million traces/s so performance is not so important anymore since I do want to do something now. The CallerMemberName feature of the C# 5 compiler is nice but I would have preferred to get direct access to the MethodHandle and not to the stringified version of it. But I really would like to see a CallerType attribute implemented to fill in the generic type argument of the call site to augment the static CLR type data with run time data.

    Read the article

  • Texture2D.GetData fails to return pixel colour data

    - by Chris Charabaruk
    Because I'm using sprite sheets instead of an individual texture per sprite, I need to pass in a Rectangle when calling Texture2D.GetData() in my collision detection for per-pixel tests. Unfortunately, without fail I get an ArgumentException percolated down from an internal method inside the Texture (not Texture2D) class. My code for getting the texture data looks like this: public override Color[] GetPixelData() { Color[] data = new Color[(int)size.Product()]; Rectangle rect = new Rectangle(hframe * (int)size.X, vframe * (int)size.Y, (int)size.X, (int)size.Y); #if DEBUG if (sprite.Bounds.Contains(rect) && sprite.Format == SurfaceFormat.Color) #endif sprite.GetData(0, rect, data, 0, 1); return data; } Even with the check to ensure I'm grabbing a valid rectangle and that the texture format matches what I'm trying to get, I still get that exception, claiming "The size of the data passed in is too large or too small for this resource." Unfortunately, the debugger won't let me check the locals within the Texture.ValidateTotalSize() method where the exception originates. Has anyone else had this problem and knows how to fix it? I'm relying on AABB testing only for now, but that doesn't really work for some of my game's entities due to odd shapes, rotation and scaling.

    Read the article

  • Webservice Return Generic Result Type or Purposed Result Type

    - by hanzolo
    I'm building a webservice which returns JSON / XML / SOAP at the moment.. and I'm not entirely sure which approach for returning results is best. Which would be a better return value? A generic "transfer" type structure, which carries Generic properties or a purposed type with distinct properties: class GenericTransferObject{ public string returnVal; public string returnType; } VS class PurposedTransferObject_1{ public string Property1; } //and then building additional "types" for additional values class PurposedTransferObject_2 { public string PropertyA; public string PropertyB; } Now, this would be the serialized and returned from a web service call via some client technology, JQuery in this example. SO if I called: /GetDaysInWeek/ I would either get back: {"returnType": "DaysInWeek", "returnVal": "365" } OR {"DaysInWeek": "365"} And then it would go from there. On the one hand there's flexibilty with the 1st example. I can add "returnTypes" without needing to adjust the client other than referencing an additional "index".. but if I had to add a property, now i'm changing a structure definition.. Is there an obvious choice in this situation?

    Read the article

  • Allowing client to select data to return via REST interface

    - by CMP
    I have a rest service that is essentially a proxy to a variety of other services. So if I call GET /users/{id} It will get their user profile, as well as order history, and contact info, etc... all from various services, and aggregates them into one nice object. My problem is that each call to a different service has the potential to add time to the original request, so we would rather not get ALL the data ALL of the time if a particular client does not care about all of the pieces. A solution I have arrived at is to do something like this: GET /users/{id}?includeOrders=true&includeX=true&includeY=true... That works, and it allow me to do only what I need to, but it is cumbersome. We have added enough different data sources that there are too many parameters for that style to be useful. I could do something similar with a single integer and a bitmask or something, but that only makes it harder to read, and it does not feel very Restful. I could break it down into multiple calls so they would need to call /users/{id}/orders and /users/{id}/profile separately, but that sort of defeats the purpose of an aggregating proxy, who's purpose is to make clients jobs easier. Are there any good patterns that can help me return just enough data for each client, without making it too difficult for them to filter and select what they want?

    Read the article

  • Can someone help me with this Java Chess game please?

    - by Chris Edwards
    Hey guys, Please can someone have a look at this code and let me know whether I am on the right track with the "check_somefigure_move"s and the "check_black/white_promotion"s please? And also any other help you can give would be greatly appreciated! Thanks! P.S. I know the code is not the best implementation, but its a template I have to follow :( Code: class Moves { private final Board B; private boolean regular; public Moves(final Board b) { B = b; regular = regular_position(); } public boolean get_regular_position() { return regular; } public void set_regular_position(final boolean new_reg) { regular = new_reg; } // checking whether B represents a "normal" position or not; // if not, then only simple checks regarding move-correctness should // be performed, only checking the direct characteristics of the figure // moved; // checks whether there is exactly one king of each colour, there are // no more figures than promotions allow, and there are no pawns on the // first or last rank; public boolean regular_position() { int[] counts = new int[256]; for (char file = 'a'; file <= 'h'; ++file) for (char rank = '1'; rank <= '8'; ++rank) ++counts[(int) B.get(file,rank)]; if (counts[Board.white_king] != 1 || counts[Board.black_king] != 1) return false; if (counts[Board.white_pawn] > 8 || counts[Board.black_pawn] > 8) return false; int count_w_promotions = 0; count_w_promotions += Math.max(counts[Board.white_queen]-1,0); count_w_promotions += Math.max(counts[Board.white_rook]-2,0); count_w_promotions += Math.max(counts[Board.white_bishop]-2,0); count_w_promotions += Math.max(counts[Board.white_knight]-2,0); if (count_w_promotions > 8 - counts[Board.white_pawn]) return false; int count_b_promotions = 0; count_b_promotions += Math.max(counts[Board.black_queen]-1,0); count_b_promotions += Math.max(counts[Board.black_rook]-2,0); count_b_promotions += Math.max(counts[Board.black_bishop]-2,0); count_b_promotions += Math.max(counts[Board.black_knight]-2,0); if (count_b_promotions > 8 - counts[Board.black_pawn]) return false; for (char file = 'a'; file <= 'h'; ++file) { final char fig1 = B.get(file,'1'); if (fig1 == Board.white_pawn || fig1 == Board.black_pawn) return false; final char fig8 = B.get(file,'8'); if (fig8 == Board.white_pawn || fig8 == Board.black_pawn) return false; } return true; } public boolean check_normal_white_move(final char file0, final char rank0, final char file1, final char rank1) { if (! Board.is_valid_white_figure(B.get(file0,rank0))) return false; if (! B.is_empty(file1,rank1) && ! Board.is_valid_black_figure(B.get(file1,rank1))) return false; if (B.get_active_colour() != 'w') return false; if (! check_move_simple(file0,rank0,file1,rank1)) return false; if (! regular) return true; final Board test_board = new Board(B); test_board.normal_white_move_0(file0,rank0,file1,rank1); final Moves test_move = new Moves(test_board); final char[] king_pos = test_move.white_king_position(); assert(king_pos.length == 2); return test_move.black_not_attacking(king_pos[0],king_pos[1]); } public boolean check_normal_black_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED THE CHECK NORMAL BLACK MOVE BASED ON THE CHECK NORMAL WHITE MOVE if (! Board.is_valid_black_figure(B.get(file0,rank0))) return false; if (! B.is_empty(file1,rank1) && ! Board.is_valid_white_figure(B.get(file1,rank1))) return false; if (B.get_active_colour() != 'b') return false; if (! check_move_simple(file0,rank0,file1,rank1)) return false; if (! regular) return true; final Board test_board = new Board(B); test_board.normal_black_move_0(file0,rank0,file1,rank1); final Moves test_move = new Moves(test_board); final char[] king_pos = test_move.black_king_position(); assert(king_pos.length == 2); return test_move.white_not_attacking(king_pos[0],king_pos[1]); } // for checking a normal move by just applying the move-rules private boolean check_move_simple(final char file0, final char rank0, final char file1, final char rank1) { final char fig = B.get(file0,rank0); if (fig == Board.white_king || fig == Board.black_king) return check_king_move(file0,rank0,file1,rank1); if (fig == Board.white_queen || fig == Board.black_queen) return check_queen_move(file0,rank0,file1,rank1); if (fig == Board.white_rook || fig == Board.black_rook) return check_rook_move(file0,rank0,file1,rank1); if (fig == Board.white_bishop || fig == Board.black_bishop) return check_bishop_move(file0,rank0,file1,rank1); if (fig == Board.white_knight || fig == Board.black_knight) return check_knight_move(file0,rank0,file1,rank1); if (fig == Board.white_pawn) return check_white_pawn_move(file0,rank0,file1,rank1); else return check_black_pawn_move(file0,rank0,file1,rank1); } private boolean check_king_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED KING MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange <= 1 && fileChange >= -1 && rankChange <= 1 && rankChange >= -1; } private boolean check_queen_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED QUEEN MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange <=8 && fileChange >= -8 && rankChange <= 8 && rankChange >= -8; } private boolean check_rook_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED ROOK MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange <=8 || fileChange >= -8 || rankChange <= 8 || rankChange >= -8; } private boolean check_bishop_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED BISHOP MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange <= 8 && rankChange <= 8 || fileChange <= 8 && rankChange >= -8 || fileChange >= -8 && rankChange >= -8 || fileChange >= -8 && rankChange <= 8; } private boolean check_knight_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED KNIGHT MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; /* IS THIS THE CORRECT WAY? * return fileChange <= 1 && rankChange <= 2 || fileChange <= 1 && rankChange >= -2 || fileChange <= 2 && rankChange <= 1 || fileChange <= 2 && rankChange >= -1 || fileChange >= -1 && rankChange <= 2 || fileChange >= -1 && rankChange >= -2 || fileChange >= -2 && rankChange <= 1 || fileChange >= -2 && rankChange >= -1;*/ // OR IS THIS? return fileChange <= 1 || fileChange >= -1 || fileChange <= 2 || fileChange >= -2 && rankChange <= 1 || rankChange >= - 1 || rankChange <= 2 || rankChange >= -2; } private boolean check_white_pawn_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED PAWN MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange == 0 && rankChange <= 1; } private boolean check_black_pawn_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED PAWN MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange == 0 && rankChange >= -1; } public boolean check_white_kingside_castling() { // only demonstration code: final char c = B.get_white_castling(); if (c == '-' || c == 'q') return false; if (B.get_active_colour() == 'b') return false; if (B.get('e','1') != 'K') return false; if (! black_not_attacking('e','1')) return false; if (! free_white('f','1')) return false; // XXX return true; } public boolean check_white_queenside_castling() { // only demonstration code: final char c = B.get_white_castling(); if (c == '-' || c == 'k') return false; if (B.get_active_colour() == 'b') return false; // ADDED BASED ON KINGSIDE CASTLING if (B.get('e','1') != 'Q') return false; if (! black_not_attacking('e','1')) return false; if (! free_white('f','1')) return false; // XXX return true; } public boolean check_black_kingside_castling() { // only demonstration code: final char c = B.get_black_castling(); if (c == '-' || c == 'q') return false; if (B.get_active_colour() == 'w') return false; // ADDED BASED ON CHECK WHITE if (B.get('e','8') != 'K') return false; if (! black_not_attacking('e','8')) return false; if (! free_white('f','8')) return false; // XXX return true; } public boolean check_black_queenside_castling() { // only demonstration code: final char c = B.get_black_castling(); if (c == '-' || c == 'k') return false; if (B.get_active_colour() == 'w') return false; // ADDED BASED ON KINGSIDE CASTLING if (B.get('e','8') != 'Q') return false; if (! black_not_attacking('e','8')) return false; if (! free_white('f','8')) return false; // XXX return true; } public boolean check_white_promotion(final char pawn_file, final char figure) { // XXX // ADDED CHECKING FOR CORRECT FIGURE AND POSITION - ALTHOUGH IT SEEMS AS THOUGH // PAWN_FILE SHOULD BE PAWN_RANK, AS IT IS THE REACHING OF THE END RANK THAT // CAUSES PROMOTION OF A PAWN, NOT FILE if (figure == P && pawn_file == 8) { return true; } else return false; } public boolean check_black_promotion(final char pawn_file, final char figure) { // XXX // ADDED CHECKING FOR CORRECT FIGURE AND POSITION if (figure == p && pawn_file == 1) { return true; } else return false; } // checks whether black doesn't attack the field: public boolean black_not_attacking(final char file, final char rank) { // XXX return true; } public boolean free_white(final char file, final char rank) { // XXX return black_not_attacking(file,rank) && B.is_empty(file,rank); } // checks whether white doesn't attack the field: public boolean white_not_attacking(final char file, final char rank) { // XXX return true; } public boolean free_black(final char file, final char rank) { // XXX return white_not_attacking(file,rank) && B.is_empty(file,rank); } public char[] white_king_position() { for (char file = 'a'; file <= 'h'; ++file) for (char rank = '1'; rank <= '8'; ++rank) if (B.get(file,rank) == Board.white_king) { char[] result = new char[2]; result[0] = file; result[1] = rank; return result; } return new char[0]; } public char[] black_king_position() { for (char file = 'a'; file <= 'h'; ++file) for (char rank = '1'; rank <= '8'; ++rank) if (B.get(file,rank) == Board.black_king) { char[] result = new char[2]; result[0] = file; result[1] = rank; return result; } return new char[0]; } public static void main(final String[] args) { // checking regular_position { Moves m = new Moves(new Board()); assert(m.regular_position()); m = new Moves(new Board("8/8/8/8/8/8/8/8 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("KK6/8/8/8/8/8/8/8 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("kk6/8/8/8/8/8/8/8 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/8/8/8/8/8/8/8 w - - 0 1")); assert(m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/8 w - - 0 1")); assert(m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/n7 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/N7 w - - 0 1")); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/b7 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/B7 w - - 0 1")); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/r7 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/R7 w - - 0 1")); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/q7 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/Q7 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kkp5/8/8/8/8/8/8/8 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("KkP5/8/8/8/8/8/8/8 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/8/8/8/8/8/8/7p w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/8/8/8/8/8/8/7P w - - 0 1")); assert(!m.regular_position()); } // checking check_white/black_king/queenside_castling { Moves m = new Moves(new Board("4k2r/8/8/8/8/8/8/4K2R w Kk - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("4k2r/8/8/8/8/8/8/4K2R b Kk - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("4k2r/4pppp/8/8/8/8/4PPPP/4K2R w KQkq - 0 1")); assert(m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("4k2r/4pppp/8/8/8/8/4PPPP/4K2R b KQkq - 0 1")); assert(!m.check_white_kingside_castling()); assert(m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/8/8/8/8/8/8/R3K3 w Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/8/8/8/8/8/8/R3K3 b Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/p7/8/8/8/8/8/R3K3 w Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/p7/8/8/8/8/8/R3K3 b Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/p7/8/8/8/n7/8/R3K3 w Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/p7/B7/8/8/8/8/R3K3 b Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); // XXX } } }

    Read the article

  • How do i return integers from a string ?

    - by kannan.ambadi
    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:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Suppose you are passing a string(for e.g.: “My name has 1 K, 2 A and 3 N”)  which may contain integers, letters or special characters. I want to retrieve only numbers from the input string. We can implement it in many ways such as splitting the string into an array or by using TryParse method. I would like to share another idea, that’s by using Regular expressions. All you have to do is, create an instance of Regular Expression with a specified pattern for integer. Regular expression class defines a method called Split, which splits the specified input string based on the pattern provided during object initialization.     We can write the code as given below:   public static int[] SplitIdSeqenceValues(object combinedArgs)         {             var _argsSeperator = new Regex(@"\D+", RegexOptions.Compiled);               string[] splitedIntegers = _argsSeperator.Split(combinedArgs.ToString());               var args = new int[splitedIntegers.Length];               for (int i = 0; i < splitedIntegers.Length; i++)                 args[i] = MakeSafe.ToSafeInt32(splitedIntegers[i]);                           return args;         }    It would be better, if we set to RegexOptions.Compiled so that the regular expression will have performance boost by faster compilation.   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:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Happy Programming  :))   

    Read the article

  • Returning in a static initializer

    - by Martijn Courteaux
    Hello, This isn't valid code: public class MyClass { private static boolean yesNo = false; static { if (yesNo) { System.out.println("Yes"); return; // The return statement is the problem } System.exit(0); } } This is a stupid example, but in a static class constructor we can't return;. Why? Are there good reasons for this? Does someone know something more about this? So the reason why I should do return is to end constructing there. Thanks

    Read the article

  • Returning in a static class constructor

    - by Martijn Courteaux
    Hello, This isn't valid code: public class MyClass { private static boolean yesNo = false; static { if (yesNo) { System.out.println("Yes"); return; // The return statement is the problem } System.exit(0); } } This is a stupid example, but in a static class constructor we can't return;. Why? Are there good reasons for this? Does someone know something more about this? So the reason why I should do return is to end constructing there. Thanks

    Read the article

  • FORTRAN function returning an array causes a segfault (calling from C++)

    - by Dane Larsen
    Basically, here's my problem. I'm calling someone else's FORTRAN functions from my C++ code, and it's giving me headaches. Some code: function c_error_message() character(len = 255) :: c_error_message errmsg(1:9) = 'ERROR MSG' return end That's the FORTRAN function. My first question is: Is there anything in there that would cause a segfault? If not, then second: What does that return? A pointer? I'm trying to call it with the following C statement: char *e = c_error_message_(); That causes a segfault. c_error_message(); That too causes a segfault. I declared c_error_message_() earlier on with the following code: extern"C" { char* c_error_message_(); } Would declaring a function with a different return type than the actual return type cause a segfault? I'm at a loss. Thanks for any replies.

    Read the article

  • C vs C++ function questions

    - by james
    I am learning C, and after starting out learning C++ as my first compiled language, I decided to "go back to basics" and learn C. There are two questions that I have concerning the ways each language deals with functions. Firstly, why does C "not care" about the scope that functions are defined in, whereas C++ does? For example, int main() { donothing(); return 0; } void donothing() { } the above will not compile in a C++ compiler, whereas it will compile in a C compiler. Why is this? Isn't C++ mostly just an extension on C, and should be mostly "backward compatible"? Secondly, the book that I found (Link to pdf) does not seem to state a return type for the main function. I check around and found other books and websites and these also commonly do not specify return types for the main function. If I try to compile a program that does not specify a return type for main, it compiles fine (although with some warnings) in a C compiler, but it doesn't compile in a C++ compiler. Again, why is that? Is it better style to always specify the return type as an integer rather than leaving it out? Thanks for any help, and just as a side note, if anyone can suggest a better book that I should buy that would be great!

    Read the article

  • MIPS return address in main

    - by Alexander
    I am confused why in the code below I need to decrement the stack pointer and store the return address again. If I don't do that... then PCSpim keeps on looping.. Why is that? ######################################################################################################################## ### main ######################################################################################################################## .text .globl main main: addi $sp, $sp, -4 # Make space on stack sw $ra, 0($sp) # Save return address # Start test 1 ############################################################ la $a0, asize1 # 1st parameter: address of asize1[0] la $a1, frame1 # 2nd parameter: address of frame1[0] la $a2, window1 # 3rd parameter: address of window1[0] jal vbsme # call function # Printing $v0 add $a0, $v0, $zero # Load $v0 for printing li $v0, 1 # Load the system call numbers syscall # Print newline. la $a0, newline # Load value for printing li $v0, 4 # Load the system call numbers syscall # Printing $v1 add $a0, $v1, $zero # Load $v1 for printing li $v0, 1 # Load the system call numbers syscall # Print newline. la $a0, newline # Load value for printing li $v0, 4 # Load the system call numbers syscall # Print newline. la $a0, newline # Load value for printing li $v0, 4 # Load the system call numbers syscall ############################################################ # End of test 1 lw $ra, 0($sp) # Restore return address addi $sp, $sp, 4 # Restore stack pointer jr $ra # Return ######################################################################################################################## ### vbsme ######################################################################################################################## #.text .globl vbsme vbsme: addi $sp, $sp, -4 # create space on the stack pointer sw $ra, 0($sp) # save return address exit: add $v1, $t5, $zero # (v1) x coordinate of the block in the frame with the minimum SAD add $v0, $t4, $zero # (v0) y coordinate of the block in the frame with the minimum SAD lw $ra, 0($sp) # restore return address addi $sp, $sp, 4 # restore stack pointer jr $ra # return If I delete: addi $sp, $sp, -4 # create space on the stack pointer sw $ra, 0($sp) # save return address and lw $ra, 0($sp) # restore return address addi $sp, $sp, 4 # restore stack pointer on vbsme: PCSpim keeps on running... Why??? I shouldn't have to increment/decrement the stack pointer on vbsme and then do the jr again right? The jal in main is supposed to handle that

    Read the article

  • Correct handling of return data

    - by Serhiy
    Hello, I have a question related to correct handling of returns of the DAO library I'm writing for one project. This library probably is going to be used by another people and I want to do it correctly. So I would like to know, how I should deal with return statements of the functions of my DAO. Example 1 I have function to getCustomer which should return String. In case query doesn't return any result should I return null, empty string or throw some kind of Exception? Example 2 I have function getCutomerList which return ArrayList. In case query doesn't return any result should I return null, empty ArrayList or throw some Exception? Example 3 Some sql exception was detected, what should I do: throw exception or do try..catch of the block where it can occur? What is the "good" practice or "best" practice to apply in my case? Thanks on advance, Serhiy.

    Read the article

  • BASH Scripting: Check If running with sudo/superuser, if not, dont run, return error

    - by EvilPhoenix
    This is something I've been curious about. I make a lot of small bash scripts (.sh files) to do tasks that I routinely do. Some of those tasks require everything to be ran as superuser. I've been curious: Is it possible to, within the BASH script prior to everything being run, check if the script is being run as superuser, and if not, print a message saying You must be superuser to use this script, then subsequently terminate the script itself. The other side of that is I'd like to have the script run when the user is superuser, and not generate the error. Any ideas on coding (if statements, etc.) on how to execute the aforementioned?

    Read the article

  • Can't return to stock Android

    - by kurt
    Whenever I try and uncompress the tar file, I get this: tar (child): nakasi-jro03d-factory-e102ba72.tg: Cannot open: No such file or directory tar (child): Error is not recoverable: exiting now tar: Child returned status 2 tar: Error is not recoverable: exiting now I'm fairly new to Ubuntu. So I'm pretty sure that's my fault. So I just compress it manually using the GUI. But when I try to flash it, I get sudo: ./flash-all.sh: command not found Please help.

    Read the article

  • Return to the old C days.

    - by RPK
    Long back I used to program on C and than VB exploitation changed the career path. After VB came the .NET that proved to be a HoneyPot of Microsoft for old VB programmers and frustrated programmers of other hard to learn languages. The label on this HoneyPot was: "Getting things done." I now want to contribute to the Linux and other GNU projects. I feel whatever programming language you learn today, but if programming is your bread-and-butter, you must remain in touch with C. Many things have changed now. From the old Turbo-C for DOS to the present ...? Please advise me how to get back on the C track again. Reading again whole thing, chapter-by-chapter is not possible now, but I can learn by writing small utilities type of things, but sure GUI based. And yes, I hope, learning is going to be easy now with so many live forums and active community spots like StackOverflow etc.

    Read the article

< Previous Page | 4 5 6 7 8 9 10 11 12 13 14 15  | Next Page >