Compiler Error C3490

'var' cannot be modified because it is being accessed through a const object

A lambda expression that is declared in a const method cannot modify non-mutable member data.

To correct this error

• Remove the const modifier from your method declaration.

Examples

The following example generates C3490 because it modifies the member variable _i in a const method:

// C3490a.cpp
// compile with: /c

class C
{
   void f() const
   {
      auto x = [=]() { _i = 20; }; // C3490
   }

   int _i;
};

The following example resolves C3490 by removing the const modifier from the method declaration:

// C3490b.cpp
// compile with: /c

class C
{
   void f()
   {
      auto x = [=]() { _i = 20; };
   }

   int _i;
};

See also

Lambda Expressions