__try_cast (C++)

Performs the specified cast or throws an exception if the cast fails.

__try_cast < type-id > ( expression )

Remarks

The __try_cast keyword (similar in behavior to dynamic_cast) provides support for automatically throwing an exception (of type System::InvalidCastException) whenever the specified casting operation fails. For more information on __try_cast, see 7.5.2 __try_cast.

The __try_cast keyword can be used during the testing phase of your application, automatically alerting you to possible casting failures.

Example

In the following example, an attempt to cast a pointer (of Derived type) to another pointer (of MoreDerived type) is made. If the cast fails, it is caught and reported by the catch block:

// keyword__try_cast.cpp
// compile with: /clr
#using <mscorlib.dll>
using namespace System;

__gc struct Base {};

__gc struct Derived : Base {};

__gc struct MoreDerived : Derived {};

int main()
{
   Base*bp = new Derived;
   try
   {
       MoreDerived* mdp = __try_cast<MoreDerived*>(bp);
   }
   catch(System::InvalidCastException*)
   {
       Console::WriteLine("Could not cast 'bp' to MoreDerived*");
   }
   return 0;
}

Output

Could not cast 'bp' to MoreDerived*

See Also

Managed Extensions for C++ Reference | __gc | dynamic_cast | Handling Exceptions Using Managed Extensions for C++ | C++ Keywords