I keep getting an invalid initializer error in this line:
StackObject_t new = (StackObject_t*)malloc(sizeof(StackObject_t)); The StackObject_t type is defined as such:
typedef struct stackObject* pStackObject_t; typedef struct stackObject { void* obj; pStackObject_t next; } StackObject_t; and this is the exact error I get: 
First of all, you should not cast the result of malloc as it can hide errors and C automatically casts void* to the correct pointer type. Secondly, your issue is because you have StackObject_t as the type of the variable but malloc returns a StackObject_t*. You can fix this by changing your line to StackObject_t* new = ... so the types match up.
malloc returns a void *, not StackObject_t*. Also, C automatically converts void * to other pointer types. It is a conversion, which is an operation that is performed. It is not a cast, which is an explicit operator in source code.It doesn't work for the same reason as int* ptr; int i = ptr; doesn't work. A pointer is not a valid initializer to an int.
The clang compiler gives a better diagnostic:
warning: incompatible pointer to integer conversion initializing 'StackObject_t' with an expression of type 'StackObject_t *'; dereference with * [-Wint-conversion]
Aha, StackObject_t is not compatible with StackObject_t *. You probably meant to write:
StackObject_t* ptr = malloc(sizeof *ptr); Details: "Pointer from integer/integer from pointer without a cast" issues
StackObject_t *) to a thing (StackObject_t). Also, recommend not using the variable namenewbecause this is a reserved word in C++. This is fully legal in C, but it's a good habit to avoid C++ keywords just to make life easier if/when you step up to C++newas identifier is a good way to get a warning if you accidentally put it in a C++ compiler.