again "undefined symbol" in runtime, c++
I have a data type and I can instantiate a variable of that type. like this:
FetchAddr faddr(VirtualMemoryAddress( 0x0a ));
The definition of FetchAdr is:
struct FetchAddr {
VirtualMemoryAddress theAddress;
FetchAddr(VirtualMemoryAddress anAddress)
: theAddress(anAddress)
{ }
};
开发者_C百科Now I have a class that faddr is a private (or public) variable
class FLEXUS_COMPONENT(BPred) {
static FetchAddr faddr;
public:
FLEXUS_COMPONENT_CONSTRUCTOR(BPred)
: base( FLEXUS_PASS_CONSTRUCTOR_ARGS )
{
faddr = VirtualMemoryAddress( 0x0a );
}
...
}
Assume the macros are defined properly.
The code compiles and links without any problem. However when I start the program, it says:
"undefined symbol: _ZN6nBPred14BPredComponent8faddr"
it says there no symbol for faddr.
any idea about that?
When you declare a static member you also have to define it somewhere, like in a .cpp file. And also remember to link to this file.
Problem number 2 - FetchAddr
doesn't have a default constructor.
If you need to have faddr
as a static member of the class, you also need to give it a value when it is defined, like:
FetchAddr FLEXUS_COMPONENT(BPred)::faddr(VirtualMemoryAddress( 0x0a ));
That creates an faddr
that is shared by all FLEXUS_COMPONENT(BPred)
objects.
If you rather have it that each object has its own copy of the faddr
variable, you can make it non-static and initialize it in the constructor:
class FLEXUS_COMPONENT(BPred) {
FetchAddr faddr;
public:
FLEXUS_COMPONENT_CONSTRUCTOR(BPred)
: base( FLEXUS_PASS_CONSTRUCTOR_ARGS ),
faddr(VirtualMemoryAddress( 0x0a ))
{ }
// ...
};
You must define the static variable elsewhere.
FetchAddr FLEXUS_COMPONENT(BPred) :: faddr;
In a single TU.
Try compiling with the -Wl,--no-undefined
so that the linker will refuse to complete the link if there is even a single symbol which is not defined in a library or any other dependencies.
faddr
has not been properly linked and without seeing more of your program, it is hard to tell what else is going on.
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