Actually, there is nothing wrong with public inheritance of std::vector. If you need this, just do that. I would suggest doing that only if it is really necessary. Only if you can’t do what you want with free functions (e.g. should keep some state). The problem is that MyVector is a new entity. It means … 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
The difference is that with std::pair you need to specify the types of both elements, whereas std::make_pair will create a pair with the type of the elements that are passed to it, without you needing to tell it. That’s what I could gather from various docs anyways. See this example from http://www.cplusplus.com/reference/std/utility/make_pair/ pair <int,int> one; … Read more
With GCC 4.1.2, to print the whole of a std::vector<int> called myVector, do the following: print *(myVector._M_impl._M_start)@myVector.size() To print only the first N elements, do: print *(myVector._M_impl._M_start)@N Explanation This is probably heavily dependent on your compiler version, but for GCC 4.1.2, the pointer to the internal array is: myVector._M_impl._M_start And the GDB command to print … Read more
A deque is somewhat recursively defined: internally it maintains a double-ended queue of chunks of fixed size. Each chunk is a vector, and the queue (“map” in the graphic below) of chunks itself is also a vector. There’s a great analysis of the performance characteristics and how it compares to the vector over at CodeProject. … Read more
Try this: vector<Type>::iterator nth = v.begin() + index;
The C++ way would be to use std::stringstream or just plain string concatenations. C++ strings are mutable so the performance considerations of concatenation are less of a concern. with regards to formatting, you can do all the same formatting on a stream, but in a different way, similar to cout. or you can use a … Read more
Using the following: g++ -O3 Time.cpp -I <MyBoost> ./a.out UseArray completed in 2.196 seconds UseVector completed in 4.412 seconds UseVectorPushBack completed in 8.017 seconds The whole thing completed in 14.626 seconds So array is twice as quick as vector. But after looking at the code in more detail this is expected; as you run across … Read more
As Cubbi pointed out in one of the comments, std::wstring_convert (C++11) provides a neat simple solution (you need to #include <locale> and <codecvt>): std::wstring string_to_convert; //setup converter using convert_type = std::codecvt_utf8<wchar_t>; std::wstring_convert<convert_type, wchar_t> converter; //use converter (.to_bytes: wstr->str, .from_bytes: str->wstr) std::string converted_str = converter.to_bytes( string_to_convert ); I was using a combination of wcstombs and tedious … Read more
The best thing to do is to use the algorithm remove_if and isspace: remove_if(str.begin(), str.end(), isspace); Now the algorithm itself can’t change the container(only modify the values), so it actually shuffles the values around and returns a pointer to where the end now should be. So we have to call string::erase to actually modify the … Read more