compile-time

Possible Duplicate: Is it possible to write a C++ template to check for a function's existence? say there are 2 classes: struct A{ int GetInt(){ return 10; } }; struct B{ int m; }; I want to use object of type A or B in following function tempate< typename T > int GetInt( const T & t ) { //if it's A, I'll call: return t.GetInt(); //if its' B, I'll call: return t.m; } Now, because there are whole bunch of classes, some contain GetInt(), some don't, I don't want to write specialization for each type, I only want to distinguish them by ' containing GetInt() or not in compile time ', how should I

Edit: In the initial question had a wrong formula and the algorithm tried was doing something completely different than what was intended. I apologise and I decided to rewrite the question to eliminate all the confusion. I need to compute at compile time (the result will be used as a non-type template parameter) the minimum number of bits needed to store n different states: constexpr unsigned bitsNeeded(unsigned n); or via template The results should be: +-----------+--------+ | number of | bits | | states | needed | +-----------+--------+ | 0 | 0 | * or not defined | | | | 1 | 0 | | | | | 2 |

How can I insert compilation timestamp information into an executable I build with Visual C++ 2005? I want to be able to output something like this when I execute the program: This build XXXX was compiled at dd-mm-yy, hh:mm. where date and time reflect the time when the project was built. They should not change with each successive call of the program, unless it's recompiled. Though not your exact format, DATE will be of the format Mmm dd yyyy, while TIME will be of the format hh:mm:ss. You can create a string like this and use it in whatever print routine makes sense for you: const char

Let's suppose we have a template function with non-type parameter of const char * like this: template <const char * MESSAGE> void print() { std::cout << MESSAGE << '\n'; } Using this template wouldn't be a problem as log as the MESSAGE can be deduced at compile-time, so the following uses are legal: namespace { char namespace_message[] = "Anonymous Namespace Message"; constexpr char namespace_constexpr_message[] = "Anonymous Namespace Constexpr Message"; } char message[] = "Message"; constexpr char constexpr_message[] = "Constexpr Message"; int main() { print<namespace_message>(); print

This question already has an answer here: Is PHP compiled or interpreted? 8 answers PHP is an interpreted language, not compiled. Yet I have come across a book that mentions stuff happening in PHP at compile time, and the PHP manual states that declaring a const happens at compile-time . How is the term compile-time used in relation to PHP since PHP isn't compiled? If it is just meant as "when the script is read and translated into the interpreters subroutines", then what is the difference between the terms compile-time and run-time? PHP source code goes through a step where it is compiled

Considering : double data; double array[10]; std::vector<int> vec(4, 100); MyClass myclass; Is there a difference between : sizeof(double); sizeof(double[10]); sizeof(std::vector<int>); sizeof(MyClass); and sizeof(data); sizeof(array); sizeof(vec); sizeof(myclass); Are the two syntaxes different or strictly equivalent ? Are all of them evaluated at compile-time ? If not, which one is evaluated at run-time ? The only differences are in syntax and convenience. Syntactically, you're allowed to leave out the parentheses in one case, but not the other: double d; sizeof(double); // compiles sizeof(d