In C++20 the way that the relational operators work was changed, notably with the introduction of the spaceship <=> operator. In particular, If you only provide operator==, then a != b is rewritten to !(a == b). From [over.match.oper]/3.4: The rewritten candidate set is determined as follows: For the relational ([expr.rel]) operators, the rewritten candidates … Read more
Off the top of my head: template <class element_type> class matrix { public: matrix(size_t width, size_t height): m_stride(width), m_height(height), m_storage(width*height) { } element_type &operator()(size_t row, size_t column) { // column major return m_storage[std::slice(column, m_height, m_stride)][row]; // row major return m_storage[std::slice(row, m_stride, m_height)][column]; } private: std::valarray<element_type> m_storage; size_t m_stride; size_t m_height; }; std::valarray provides many interesting … Read more
Yes, given the same environment for the program. From the C standard ยง7.20.2.2/2, The srand function uses the argument as a seed for a new sequence of pseudo-random numbers to be returned by subsequent calls to rand. If srand is then called with the same seed value, the sequence of pseudo-random numbers shall be repeated. … Read more
There is nothing wrong in your example (except that you should add a semi-colon after the cin.tie(0) line), nor with the way iostream objects work. tie() simply guarantees the flushing of cout before cin executes an input. This is useful for the user to see the question before being asked for the answer. However, if … Read more
There are a number of differences. Some were, I believe, Boost changes that were never propagated. For example, there is no path.filename_is_dot() query (as discussed below, it would be less useful in std::filesystem anyway). There was also a good bit of late-breaking news on this front: Support for non-POSIX-like filesystems: Specify whether a string is … Read more
You can try LOCAL_CFLAGS := -std=c++11, but note that not all C++11 APIs are available with the NDK’s gnustl. Full C++14 support is available with libc++ (APP_STL := c++_shared). The alternative is to implement it yourself. #include <string> #include <sstream> template <typename T> std::string to_string(T value) { std::ostringstream os ; os << value ; return … Read more
double pow(double, int); hasn’t been removed from the spec. It has simply been reworded. It now lives in [c.math]/p11. How it is computed is an implementation detail. The only C++03 signature that has changed is: float pow(float, int); This now returns double: double pow(float, int); And this change was done for C compatibility. Clarification: 26.8 … Read more
Only partially. C++11 <string> has std::to_string for the built-in types: [n3290: 21.5/7]: string to_string(int val); string to_string(unsigned val); string to_string(long val); string to_string(unsigned long val); string to_string(long long val); string to_string(unsigned long long val); string to_string(float val); string to_string(double val); string to_string(long double val); Returns: Each function returns a string object holding the character representation … Read more
The short answer is “because C++ has moved on”. Yes, back in the late 70’s, Stroustrup intended to create an upgraded C with OOP capabilities, but that is a long time ago. By the time the language was standardized in 1998, it was no longer an OOP language. It was a multi-paradigm language. It certainly … Read more
I’ll refer to the C standard; I think the C++ standard inherits the rules for <stdint.h> / <cstdint> from C. I know that gcc implements 128-bit signed and unsigned integers, with the names __int128 and unsigned __int128 (__int128 is an implementation-defined keyword) on some platforms. Even for an implementation that provides a standard 128-bit type, … Read more