C++: Fastest method to check if all array elements are equal
int check(const int a[], int n) { while(–n>0 && a[n]==a[0]); return n!=0; }
c++
Both asterisk and ampersand in a parameter
In your expression BinaryNode * & t) BinaryNode* & t ————- —– BinaryNode pointer t is reference variable so t is reference to pointer of BinaryNode class. Pointer of the address of t? You are confused ampersand & operator in c++. that give address of an variable. but syntax is different. ampersand & in front … Read more
Is using unsigned integer overflow good practice?
Unsigned integer overflow (in the shape of wrap-around) is routinely taken advantage of in hashing functions, and has been since the year dot.
Implementing the visitor pattern using C++ Templates
This can be done in C++11 using variadic templates. Continuing from Pete’s answer: // Visitor template declaration template<typename… Types> class Visitor; // specialization for single type template<typename T> class Visitor<T> { public: virtual void visit(T & visitable) = 0; }; // specialization for multiple types template<typename T, typename… Types> class Visitor<T, Types…> : public Visitor<Types…> … Read more
How can I extend a lexical cast to support enumerated types?
You have to do two steps. Finding an integral type large enough to store the values. You could use unsigned long, but the values could be negative. Then you could use long but the values could extend into the range of unsigned long. So there is not really a fit-it-all type. There is a trick … Read more
Why does a virtual function get hidden?
Assuming you intended B to derive from A: f(int) and f() are different signatures, hence different functions. You can override a virtual function with a function that has a compatible signature, which means either an identical signature, or one in which the return type is “more specific” (this is covariance). Otherwise, your derived class function … Read more
Literal initialization for const references
So you can write code like this: void f( const string & s ) { } f( “foobar” ); Although strictly speaking what is actually happening here is not the literal being bound to a const reference – instead a temprary string object is created: string( “foobar” ); and this nameless string is bound to … Read more
How do I use google mock in C?
I found a way to be able to mock bare C functions in google-mock. The solution is to declare foobar to be a weak alias that maps to foobarImpl. In production code you do not implement foobar() and for unit tests you provide an implementation that calls a static mock object. This solution is GCC … Read more
What happens if main() does not return an int value?
If main doesn’t return int, then you have an ill-formed program and behavior is undefined. Anything can happen. Your program might crash, or it might run as though nothing were wrong at all. Let’s suppose main returned something other than int, and your compiler and linker allowed the program to be made. The caller doesn’t … Read more
List of common C++ Optimization Techniques [closed]
I will echo what others have said: a better algorithm is going to win in terms of performance gains. That said, I work in image processing, which as a problem domain can be stickier. For example, many years ago I had a chunk of code that looked like this: void FlipBuffer(unsigned char *start, unsigned char … Read more