It is just a linker error: the "undefined reference" is a hint that you may have forgotten to define something.
That said, in this case it may be better to make Update a pure virtual instead:
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Type: Posts; User: laserlight
It is just a linker error: the "undefined reference" is a hint that you may have forgotten to define something.
That said, in this case it may be better to make Update a pure virtual instead:
...