static map initialization in c++ - c++

Question

There are a number of similar questions, in fact I composed the following code from several other posts. Unfortunately I still have one error I can't seem to crack - and although I did a lot of c++ development that was 15 years ago.
I want to make a simple static look-up table using a map.
Here is the code so far (the code css seems to not render it very well):
enum RegionCodeEnum
{
One,
Two,
Three
};
enum DeviceCodeEnum
{
AAA,
BBB,
CCC
};
class LookupTable
{
friend class constructor;
struct constructor
{
constructor()
{
table[One] = AAA;
table[Two] = AAA;
table[Three] = CCC;
}
};
static constructor cons;
public:
LookupTable(void);
static DeviceCodeEnum GetDeviceFromRegion(RegionCodeEnum RegionCode);
private:
static map<RegionCodeEnum, DeviceCodeEnum> table;
};
LookupTable::constructor LookupTable::cons;
LookupTable::LookupTable(void)
{
}
DeviceCodeEnum LookupTable::GetDeviceFromRegion(RegionCodeEnum RegionCode)
{
return table[RegionCode];
}
From else where in the code I have this code:
DeviceCodeEnum code= LookupTable::GetDeviceFromRegion(One);
The compile error I get is:
error LNK2001: unresolved external symbol "private: static class std::map<enum RegionCodeEnum,enum DeviceCodeEnum,struct std::less<enum DeviceCodeEnum>,class std::allocator<struct std::pair<enum RegionCodeEnum const ,enum DeviceCodeEnum> > > LookupTable::table" (?table#LookupTable##0V?$map#W4RegionCodeEnum##W41#U?$less#W4DeviceCodeEnum###std##V?$allocator#U?$pair#$$CBW4DeviceCodeEnum##W41##std###3##std##A) C:\_dev\temp\test\main.obj Refactor01
Any thoughts?

Answer 1

You are missing the definition for table. Somewhere in your code it should say:
map<RegionCodeEnum, DeviceCodeEnum> LookupTable::table;
just as you did for constructor cons.