How does the following work? #include <limits> int main() { const int* const foo = &std::numeric_limits<int> ::digits; } I was under the impression that in order to take an address of a static const-ant member we had to physically define it in some translation unit in order to please the linker. That said, after looking at the prep...
Hello, Am struggling a bit with this. Am declaring: BYTE *pImage = NULL; Used in call: m_pMyInterface->GetImage(i, &imageSize, &pImage); Visual C++ 2003 compiler error: error C2664: 'CJrvdInterface::GetImage' : cannot convert parameter 3 from 'BYTE **__w64 ' to 'BYTE **& ' A reference that is not to 'const' cannot be boun...
The following code does not compile: #include <iostream> class Foo { std::string s; public: const std::string& GetString() const { return s; } std::string* GetString() { return &s; } }; int main(int argc, char** argv){ Foo foo; const std::string& s = foo.GetString(); // error return 0; } I get the following error: const...
Suppose i have: class A { A(A& foo){ ..... } A& operator=(const A& p) { } } ... A lol; ... A wow(...) { return lol; } ... ... A stick; stick = wow(...); Then I'll get a compile error in the last line. But if I add 'const' before 'A&', its ok. I want to know why. Where it's exactly the problem? I dont get why it shoul...
I want to do something like this, but I cannot get a cooperative syntax. static const UIColor *colorNavbar = [UIColor colorWithRed: 197.0/255.0 green: 169.0/255.0 blue: 140.0/255.0 alpha: 1.0]; I suppose that I could define macros, but they are ugly. ...
if I want to construct a const char * out of several primitive type arguments, is there a way to build the string using a similar to the printf? ...
I can initialize float32x4_t like this: const float32x4x4_t zero = { 0.0f, 0.0f, 0.0f, 0.0f }; But this code makes an error Incompatible types in initializer: const float32x4x4_t one = { 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, }; float32x4x4_t is 4x4 matrix bui...
I tried to pass const with vector it works: Ex: void damn(const vector <bool> &bb) { for (int i=0; i<bb.size(); i++) cout<<bb[i]<<endl; } But when trying with map, it does not: void pas(const map <string, float> &mm) { cout<<mm["a"]; cout<<mm["b"]; } I wonder why it doesn't. ...
My comments on this answer got me thinking about the issues of constness and sorting. I played around a bit and reduced my issues to the fact that this code: #include <vector> int main() { std::vector <const int> v; } will not compile - you can't create a vector of const ints. Obviously, I should have known this (and intellect...
I'm working in a C, and C++ program. We used to be compiling without the make-strings-writable option. But that was getting a bunch of warnings, so I turned it off. Then I got a whole bunch of errors of the form "Cannot convert const char* to char* in argmuent 3 of function foo". So, I went through and made a whole lot of changes to fix...
What is the simplest and least obtrusive way to indicate to the compiler, whether by means of compiler options, #defines, typedefs, or templates, that every time I say T, I really mean T const? I would prefer not to make use of an external preprocessor. Since I don't use the mutable keyword, that would be acceptable to repurpose to indic...
In the standard library of C++ the value std::numeric_limits<T>::max() is specified as a function. Further properties of a specific type are given as constants (like std::numeric_limits<T>::is_signed). All constants that are of type T are given as functions, whereas all other constants are given as, well, constant values. Whats the rati...
I know that you can create global constants in terms of each other using string concatenation: define('FOO', 'foo'); define('BAR', FOO.'bar'); echo BAR; will print 'foobar'. However, I'm getting an error trying to do the same using class constants. class foobar { const foo = 'foo'; const foo2 = self::foo; const bar = self::f...
My example is as below. I found out the problem is with "const" in function void test's parameter. I don't know why the compiler does not allow. Could anybody tell me? Thanks. vector<int> p; void test(const vector<int> &blah) { vector<int>::iterator it; for (it=blah.begin(); it!=blah.end(); it++) { cout<<*it<<" "; } }...
I'm working on a program that's supposed to represent a graph. My issue is in my printAdjacencyList function. Basically, I have a Graph ADT that has a member variable "nodes", which is a map of the nodes of that graph. Each Node has a set of Edge* to the edges it is connected to. I'm trying to iterate across each node in the graph and ea...
Hi, I'm thinking of using pure/const functions more heavily in my C++ code. (pure/const attribute in GCC) However, I am curious how strict I should be about it and what could possibly break. The most obvious case are debug outputs (in whatever form, could be on cout, in some file or in some custom debug class). I probably will have a ...
pure is a function attribute which says that a function does not modify any global memory. const is a function attribute which says that a function does not read/modify any global memory. Given that information, the compiler can do some additional optimisations. Example for GCC: float sigmoid(float x) __attribute__ ((const)); float c...
Is there any way to define a constant for an entire namespace, rather than just within a class? For example: namespace MyNamespace { public const string MY_CONST = "Test"; static class Program { } } Gives a compile error as follows: Expected class, delegate, enum, interface, or struct ...
The following example is working when I manualy replace T wirh char *, but why is not working as it is: template <typename T> class A{ public: A(const T _t) { } }; int main(){ const char * c = "asdf"; A<char *> a(c); } When compiling with gcc, I get this error: test.cpp: In function 'int main()': test.cpp:10: error: invali...
I'm wondering if anyone can explain the following to me: If I write int i = 0; float* pf = i; I get a compile error (gcc 4.2.1): error: invalid conversion from ‘int’ to ‘float*’ Makes sense - they are obviously two completely different types. But if instead I write const int i = 0; float* pf = i; It compiles without error. Wh...