The cause of the error

The error message is somewhat cryptic.

Compiling...
Errors01.cpp
C:\jnk\Errors01.cpp(29) : error C2228: 
left of '.doSomething' 
must have class/struct/union type

The cause of the error is the attempt (shown in boldface) to use a dot operator (.) when the pointer-to-member operator (->) must be used instead.

The pointer-to-member operator (->) must be used to access a member of an object stored in dynamic memory by way of a pointer variable containing the address of the object.

(The correct syntax is shown in a comment in the line immediately above the line with the error.)