C ++ error set: Undefined reference to 'sptradercontroller: writeapllog (BFL: bstring const &) appears in linkeage &)

Error description:

After make, the compilation process goes smoothly.Connection stageConnect the target file generated in the previous step with the target file in the system library to the library file.) Error:

../Lib/linux_gcc4/libsptlib. A (sptradercontroller. O) :(. Data. Rel. Ro. _ ztv18sptradercontroller [vtable for sptradercontroller] + 0x9c ):Undefined reference to 'sptradercontroller: writeapllog (BFL: bstring
Const &)'

Correction:

After the writeapllog () function is declared in sptradercontroller. H, it is not defined in sptradercontroller. CC.