Why use a new call with a C++ 'vector'? - Stack Overflow
2018年2月13日 · The constructor of std::vector does the same thing for the elements of the std::vector. If that is what you mean by "double allocation", then the answer is "Yes". Everyone …
new int [size] vs std::vector - Stack Overflow
2012年3月16日 · A std::vector<T> will free the allocated memory when the vector goes out of scope, a int * will not. A int * will have little to no overhead (compared to the vector), though …
Why doesn't C++ require a "new" statement to initialize std::vector?
new std::vector<my_obj*>() This expression returns a pointer. It returns a std::vector<my_obj*>*, which is not the same type as foo (the * at the end is what makes them different). foo is an …
c++ - Instantiate a new STL vector - Stack Overflow
myvectr = new vector<int>(100); // reserve some space as appropriate But you should not have a raw pointer as a member to your class (unless there is a very good reason). You will need to …
c++ - Creating a new vector using a transform - Stack Overflow
2009年2月9日 · I have a vector of integers and I want to convert it to a vector of pairs (pair consists of a bool and a int). My current code is simple like this: std::vector<int> a; …
c++ - New Operator With Vectors - Stack Overflow
2011年1月25日 · It doesn't make much sense to use vector of pointers unless the size of type you want to store in the vector is quite big. Actually when you do vector<T>::push_back(val) is it …
c++ std::vector<> vs new [] performance - Stack Overflow
2014年1月7日 · Vector maintains and array list of elements. Whereas new allocates a memory location. Vector at the back end is also creating elements with new keyword. So, new's work is …
Why should I use new Vector3? What is the difference?
2018年7月7日 · The third function initializes the vector, multiplies it by Time.deltaTime, and then calls the transform.Rotate function on this result. This would result in the intended behavior. …
Create new vector based on conditions from another vector
2018年4月9日 · How can I create a vector of equal length BUT with values -1 if 0 or 3 and 1 if 1 or 5. So with v1 = c(0, 3, 5, 1, 1, 3, 5, 0), I am expecting a ... Skip to main content
c++ - allocating vectors (or vectors of vectors) dynamically - Stack ...
2011年8月1日 · std::vector<double>* vec = new std::vector<double>(size); The latter gives you a pointer, which you have to delete. The former gives you a vector which, when it goes out of …