Search Results

Search found 4826 results on 194 pages for 'compiler directives'.

Page 146/194 | < Previous Page | 142 143 144 145 146 147 148 149 150 151 152 153  | Next Page >

• Is new int[10]() valid c++?

  - by Naveen

  While trying to answer this question I found that the code int* p = new int[10](); compiles fine with VC9 compiler and initializes the integers to 0. So my questions are: First of all is this valid C++ or is it a microsoft extension? Is it guaranteed to initialize all the elements of the array? Also, is there any difference if I do new int; or new int();? Does the latter guarantee to initialize the variable?

  Read the article

• Isses using function with variadic arguments

  - by Sausages

  I'm trying to write a logging function and have tried several different attempts at dealing with the variadic arguments, but am having problems with all of them. Here's the latest: - (void) log:(NSString *)format, ... { if (self.loggingEnabled) { va_list vl; va_start(vl, format); NSString* str = [[NSString alloc] initWithFormat:format arguments:vl]; va_end(vl); NSLog(format); } } If I call this like this: [self log:@"I like: %@", @"sausages"]; Then I get an EXC_BAD_ACCESS at the NSLog line (there's also a compiler warning that the format string is not a string literal). However if in XCode's console I do "po str" it displays "I like: sausages" so str seems ok.

  Read the article

• Why does Generic class signature requires specifying new() if type T needs instantiation ?

  - by this. __curious_geek

  I'm writing a Generic class as following. public class Foo<T> : where T : Bar, new() { public void MethodInFoo() { T _t = new T(); } } As you can see the object(_t) of type T is instantiated at run-time. To support instantiation of generic type T, language forces me to put new() in the class signature. I'd agree to this if Bar is an abstract class but why does it need to be so if Bar standard non-abstract class with public parameter-less constructor. compiler prompts following message if new() is not found. Cannot create an instance of the variable type 'T' because it does not have the new() constraint

  Read the article

• C++ standard: dereferencing NULL pointer to get a reference?

  - by shoosh

  I'm wondering about what the C++ standard says about code like this: int* ptr = NULL; int& ref = *ptr; int* ptr2 = &ref; In practice the result is that ptr2 is NULL but I'm wondering, is this just an implementation detail or is this well defined in the standard? Under different circumstances a dereferencing of a NULL pointer should result in a crash but here I'm dereferencing it to get a reference which is implemented by the compiler as a pointer so there's really no actual dereferencing of NULL.

  Read the article

• Pointer aliasing- in C++0x

  - by DeadMG

  I'm thinking about (just as an idea) disjointed pointer aliasing in C++0x. I was thinking about seeing if it could be implemented similarly to const correctness- that is, enforced by the compiler. What would be the requirements for such a thing? As this is more of a thought experiment, I'm perfectly happy to look at solutions that destroy legacy code or redefine half the language and that kind of thing. What I'd really rather not do is have, say, restrict from C99 where the programmer just promises it. It should be enforced.

  Read the article

• C++ rvalue temporaries in template

  - by aaa

  hello. Can you please explain me the difference between mechanism of the following: int function(); template<class T> void function2(T&); void main() { function2(function()); // compiler error, instantiated as int & const int& v = function(); function2(v); // okay, instantiated as const int& } is my reasoning correct with respect to instantiation? why is not first instantiated as const T&? Thank you

  Read the article

• F# match char values

  - by rwallace

  I'm trying to match an integer expression against character literals, and the compiler complains about type mismatch. let rec read file includepath = let ch = ref 0 let token = ref 0 use stream = File.OpenText file let readch() = ch := stream.Read() let lex() = match !ch with | '!' -> readch() | _ -> token := !ch ch has to be an int because that's what stream.Read returns in order to use -1 as end of file marker. If I replace '!' with int '!' it still doesn't work. What's the best way to do this?

  Read the article

• Misunderstanding function pointer - passing it as an argument

  - by Stef

  I want to pass a member function of class A to class B via a function pointer as argument. Please advise whether this road is leading somewhere and help me fill the pothole. #include <iostream> using namespace std; class A{ public: int dosomeA(int x){ cout<< "doing some A to "<<x <<endl; return(0); } }; class B{ public: B(int (*ptr)(int)){ptr(0);}; }; int main() { A a; int (*APtr)(int)=&A::dosomeA; B b(APtr); return 0; } This brilliant piece of code leaves me with the compiler error: cannot convert int (A::*)(int)' toint (*)(int)' in initialization Firstly I want it to compile. Secondly I don't want dosomeA to be STATIC.

  Read the article

• [VB.NET] Same name methods in different modules cause ambiguity.

  - by smwikipedia

  I have 2 modules. Each contains a Sub with the same name. See below: Module moduleA Public Sub f(ByVal arg1 As myType) Console.WriteLine("module A") End Sub End Module Module moduleB Public Sub f(ByVal arg1 As myType, ByVal arg2 As Boolean) Console.WriteLine("module B") End Sub End Module But the compiler complains that there's ambiguity between moduleA and moduleB. How could this be? I have totally different signatures. However, if I put the 2 methods into the same module, there's no ambiguity at all. Could someone tell me why? Many thanks.

  Read the article

• Why Does try ... catch Blocks Require Braces?

  - by Bidou

  Hello. While in other statements like if ... else you can avoid braces if there is only one instruction in a block, you cannot do that with try ... catch blocks: the compiler doesn't buy it. For instance: try do_something_risky(); catch (...) std::cerr << "Blast!" << std::endl; With the code above, g++ simply says it expects a '{' before do_something_risky(). Why this difference of behavior between try ... catch and, say, if ... else ? Thanks!

  Read the article

• Is this a valid C statement ?

  - by Philando Gullible

  Lets say I write char c[99] = {'Stack Overflow'}; in C or C++ it does compiles fine but does this valid? By valid I meant not invoking any kind of undefined or unspecified behavior. Again if I write char c[99] = 'Stack Overflow'; gcc complains about multicharacter constant which is obvious but in the above when I am enclosing within curly brackets compiler is happy! why is it so ? I also notice that puts(c); after the first statement will output 'w' precisely the last character of a general string in-place of Stack Overflow. why so ? Could somebody explain this behavior may be separately.

  Read the article

• Problem with non-copyable classes

  - by DeadMG

  I've got some non-copyable classes. I don't invoke any of the copy operators or constructor, and this code compiles fine. But then I upgraded to Visual Studio 2010 Ultimate instead of Professional. Now the compiler is calling the copy constructor- even when the move constructor should be invoked. For example, in the following snippet: inline D3D9Mesh CreateSphere(D3D9Render& render, float radius, float slices) { D3D9Mesh retval(render); /* ... */ return std::move(retval); } Error: Cannot create copy constructor, because the class is non-copyable. However, I quite explicitly moved it.

  Read the article

• Strings in ASP?

  - by TSL

  Hi All, I have some APSX code that I am trying to modify for a programmer that is out on medicaly leave. I am not an ASP guy, but rather C++ So what I want to do is delare a string, check the first 4 characters and if it is 'http' do something, if not, something else. Here is what I have: string strYT= Left(objFile, 4); if (strYT=="http") { pnlYT.Visible = true; pnlIntro.Visible = false; pnlVideo.Visible = false; } else { pnlYT.Visible = false; pnlIntro.Visible = false; pnlVideo.Visible = true; PrintText(objFile); } But I get errors like: Compiler Error Message: CS0103: The name 'Left' does not exist in the class or namespace 'ASP.zen_aspx' My googling turns up many examples of doing it just like this.....

  Read the article

• Should I use C(99) booleans ? ( also c++ booleans in c++ ?)

  - by Roman A. Taycher

  I haven't done much c programming but when I do when I need a false I put 0 when I want true I put 1, (ex. while(1)), in other cases I use things like "while(ptr)" or "if(x)". Should I try using C99 booleans, should I recommend them to others if I'm helping people new to programming learn c basics(thinking of cs 1?? students)? I'm pretty sure the Visual Studio compiler supports c99 bools, but do a lot of projects (open source and c apps in industry) compile for c89? If I don't use C bools should I at least do something like #define TRUE 1 #define FALSE 0? Also what about c++ Booleans (for c++)?

  Read the article

• Get result type of function

  - by Robert

  I want to specialize a template function declared as: template<typename Type> Type read(std::istream& is); I then have a lot of static implementations static int read_integer(std::istream& is); a.s.o. Now I'd like to do a macro so that specialization of read is as simple as: SPECIALIZE_READ(read_integer) So I figured I'd go the boost::function_traits way and declare SPECIALIZE_READ as: #define SPECIALIZE_READ(read_function) \ template<> boost::function_traits<read_function>::result_type read(std::istream& is) { \ return read_function(is); \ } but VC++ (2008) compiler complains with: 'boost::function_traits' : 'read_integer' is not a valid template type argument for parameter 'Function' Ideas ?

  Read the article

• C# Generics Multiple Inheritance Problem

  - by Ciemnl

  Can any one help me with this syntax issue with C#? I have no idea how to do it. class SomeClass<T> : SomeOtherClass<T> where T : ISomeInterface , IAnotherInterface { ... } I want SomeClass to inherit from SomeOtherClass and IAnotherInterface and for T to inherit ISomeInterface only It seems the problem is that the where keyword screws everything up so that the compiler thinks both ISomeInterface and IAnotherInterface should both be inherited by T. This problem is very annoying and I think the solution is some kind of parenthesis but I have tried and failed finding one that works. Also, switching around the order of the two items inherited from SomeClass does not work because the class inherited always has to come before any interfaces. I couldn't find any solutions on the MSDN C# generics pages and I can't beleive I'm the first person to have this problem. Thanks, any help is much appreciated!

  Read the article

• How to strip debug code during compile time in C++?

  - by juvenis

  Say I have a C++ function debugPrint(int foo). How can I most conveniently strip that from release builds? I do not want to surround every call to debugPrint with #ifdefs as it would be really time consuming. On the other hand, I want to be 100% sure that the compiler strips all the calls to that function, and the function itself from release builds. The stripping should happen also, if it's called with a parameter that results from a function call. E.g., debugPrint(getFoo());. In that case I want also the getFoo() call to be stripped. I understand that function inlining could be an option, but inlining is not guaranteed to be supported.

  Read the article

• What's the outcome if I use free with new or delete with malloc?

  - by skydoor

  It is a compiler error or runtime error? The code below can be compiled! class Base{ void g(); void h(); }; int main() { Base* p = new Base(); free(p); return 0; } However it can't be compiled with a virtual function if I declare the class Base like this class Base{ virtual void g(); void h(); }; The code below can be compiled all the time, no matter the function is virtual or not. class Base{ void g(); void h(); }; int main() { Base* p = (Base*)malloc(sizeof(Base)); delete p; return 0; }

  Read the article

• what is the best approach for to use openGL in the web?

  - by Y_Y

  I wrote a program in C++/OpenGL (using Dev-C++ compiler) for my calculus 2 class. The teacher liked the program and he requested me to somehow put it online so that instead of downloading the .exe file and run it the web browser will run it automatically just like a java applet. The question is: How if possible, can I display a C++/OpenGL program in a web browser? I am thinking of moving to JOGL which is a java interpretation of OpenGL but I rather stay in C++ since I am more familiar with it. Also is there any other better and easier 3D web base API that I can consider?

  Read the article

• I want to make a wrapped acces type for certain internals of one of classes and I have some performa

  - by Alex

  I am writing an abstract matrix class (and some concrete subclasses) for use on very differing hardwares/architectures, etc. and I want to write a row and column type that provides a transparent reference to the rows and columns of the matrix. However, I want to tune for performance, so I'd like this class to be essentially a compiler construct. In other words, I'm willing to sacrifice some dev time to making the overhead of these classes as small as possible. I assume all (small) methods would want to be virtual? Keep the structure small? Any other suggestions?

  Read the article

• Typecasting doesn't work. How to convert an object?

  - by Nastase Ion

  Hi everyone! I need to convert a custom object to a different object. How can I do that? I know that typecasting doesn't work (the only thing is does is "shuts the compiler warnings off", but nothing more). Here is a sample code: MyType* obj1; MyOtherType* obj2; obj1 = [MyType initWithData: 1]; obj2 = (MyOtherType*) obj1; if ([obj2 isMemberOfClass: [MyOtherType class]]) { NSLog(@"OK"); } else if ([obj2 isMemberOfClass: [MyType class]]) { NSLog(@"Nope"); } The result is: Nope What can I do??

  Read the article

• Why Do try ... catch Blocks Require Braces?

  - by Bidou

  Hello. While in other statements like if ... else you can avoid braces if there is only one instruction in a block, you cannot do that with try ... catch blocks: the compiler doesn't buy it. For instance: try do_something_risky(); catch (...) std::cerr << "Blast!" << std::endl; With the code above, g++ simply says it expects a '{' before do_something_risky(). Why this difference of behavior between try ... catch and, say, if ... else ? Thanks!

  Read the article

• question about copy constructor

  - by lego69

  I have this class: class A { private: int player; public: A(int initPlayer = 0); A(const A&); A& operator=(const A&); ~A(); void foo() const; }; and I have function which contains this row: A *pa1 = new A(a2); can somebody please explain what exactly is going on, when I call A(a2) compiler calls copy constructor or constructor, thanks in advance

  Read the article

• Tracking Useful Information

  - by Steve M

  What do the clever programmers here do to keep track of handy programming tricks and useful information they pick up over their many years of experience? Things like useful compiler arguments, IDE short-cuts, clever code snippets, etc. I sometimes find myself frustrated when looking up something that I used to know a year or two ago. My IE favourites probably represent a good chunk of the Internet in the late 1990s, so clearly that isn't effective (at least for me). Or am I just getting old? So.. what do you do?

  Read the article

• C++ template + typedef

  - by MMS

  What is wrong in the following code: Point2D.h template <class T> class Point2D { private: T x; T y; ... }; PointsList.h template <class T> class Point2D; template <class T> struct TPointsList { typedef std::vector <Point2D <T> > Type; }; template <class T> class PointsList { private: TPointsList <T>::Type points; //Compiler error ... }; I would like to create new user type TPointsList without direct type specification...

  Read the article

< Previous Page | 142 143 144 145 146 147 148 149 150 151 152 153  | Next Page >