c++ * new meaning code example

Example 1: new in c++

//placement new in c++
char *buf  = new char[sizeof(string)]; // pre-allocated buffer
string *p = new (buf) string("hi");    // placement new
string *q = new string("hi");          // ordinary heap allocation
/*Standard C++ also supports placement new operator, which constructs 
an object on a pre-allocated buffer. This is useful when building a 
memory pool, a garbage collector or simply when performance and exception 
safety are paramount (there's no danger of allocation failure since the memory
has already been allocated, and constructing an object on a pre-allocated
buffer takes less time):
*/

Example 2: new class * [] c++

/*
 Keyword "this"
You can use keyword "this" to refer to this instance inside a class definition.

One of the main usage of keyword this is to resolve ambiguity between the names of 
data member and function parameter. For example:
*/
class Circle {
private:
   double radius;                 // Member variable called "radius"
   ......
public:
   void setRadius(double radius) { // Function's argument also called "radius"
      this->radius = radius;
         // "this.radius" refers to this instance's member variable
         // "radius" resolved to the function's argument.
   }
   ......
}