Comment : déclarer des pointeurs intérieurs avec le mot clé const (C++/CLI)How to: Declare Interior Pointers with the const Keyword (C++/CLI)

L’exemple suivant montre comment utiliser const dans la déclaration d’un pointeur intérieur.The following sample shows how to use const in the declaration of an interior pointer.

Important

Cette fonctionnalité de langage est prise en charge par l’option du compilateur /clr, mais pas par l’option du compilateur /ZW.This language feature is supported by the /clr compiler option, but not by the /ZW compiler option.

ExempleExample

// 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);
};

Voir aussiSee also

interior_ptr (C++/CLI)interior_ptr (C++/CLI)