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 mentions it is evil to mix a vector with a new call, but why? Use of. vector<someType> *myVector = new vector<someType>();

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 std::vector<T> isn't exactly a new thing and is normally very optimized. Your bottle neck will probably be elsewhere.

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 object, std::vector<my_obj*>* is a pointer to an object. Objects (rather than pointers or references) have specific lifetimes.

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 write your own copy constructor and assignment operator.

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&lt;int&gt; a; std::vector&lt...

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 going to store a copy of val using a copy constructor T::T(T &orig) and call destructor for all elements when you do clear()

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 only to allocate, whereas the vector will not only be creating a new element but will also be organizing it into an array and incrementing size information and may be other ...

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. Basically, keep track of your order of operations.

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

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 scope, cleans up after itself.