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.
Important
This language feature is supported by the /clr compiler option, but not by the /ZW compiler option.
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 object cannot be dereferenced and changed
h_G2->msg = "test";
interior_ptr<String^ const> int_ptr_G2 = &(h_G->msg);
};