How to: Declare Interior Pointers with the const Keyword (C++/CLI)

The latest version of this topic can be found at How to: Declare Interior Pointers with the const Keyword (C++/CLI).

The following sample shows how to use const in the declaration of an interior pointer.

Example

// interior_ptr_const.cpp  
// compile with: /clr  
using namespace System;  
value struct V {   
   int i;  
};  
  
ref struct G {  
   V v;  
   String ^ msg;  
};  
  
interior_ptr<int> f( interior_ptr<V> pv ) {   
   return &(pv->i);   
}  
  
int main() {  
   int n = -1;  
   int o = -1;  
   interior_ptr<int> pn1 = &n;  
   *pn1 = 50;  
  
   V v;  
   v.i = 101;  
   V * npV = &v;   // ok: &v yields a pointer to the native heap  
  
   interior_ptr<int> pn2 = &n;  
   interior_ptr<V> pV = &(v);  
   pn2 = f(pV);  
   *pn2 = 50;  
  
   G ^pG = gcnew G;  
   pV = &(pG->v);   // ok: pV is an interior pointer  
  
   interior_ptr<int const> pn3 = &n;  
   // *pn3 = 5;   error because pn3 cannot be dereferenced and changed  
   pn3 = &o;   // OK, can change the memory location  
  
   interior_ptr<int> const pn4 = &n;     
   *pn4 = 5;   // OK because you can dereference and change pn4  
   // pn4 = &o;   error cannot change the memory location  
  
   const interior_ptr<const int> pn5 = &n;  
   // *pn5 = 5;   error cannot dereference and change pn5  
   // pn5 = &o;   error cannot change the memory location  
  
   const G ^ h_G = gcnew G;   // object is const, cannot modify any members of h_G or call any non-const methods  
   // h_G->msg = "test";   error h_G is const  
   interior_ptr<String^ const> int_ptr_G = &(h_G->msg);  
  
   G ^ const h_G2 = gcnew G;   // interior pointers to this obejct cannot be dereferenced and changed  
   h_G2->msg = "test";  
   interior_ptr<String^ const> int_ptr_G2 = &(h_G->msg);  
};  

See Also

interior_ptr (C++/CLI)