Can*t call chainActive.Tip()->nHeight in core.cpp I want to call chainActive.Tip()->nHeight in core.cpp. It is not possible, I am interested in every idea. 

https://github.com/LIMXTEC/BitSend/blob/DEV-joshafest/src/core.cpp

Here is an example :

bool GetH()
{   
    int nBlockHeight = chainActive.Tip()-&gt;nHeight;  
    if(nBlockHeight &lt; FORKX17_Main_Net ) 
        return true;    
    else 
        return false; 
    }
}

uint256 CBlockHeader::GetHash() const 
{   
    if (GetH())     
    {
        return HashX11(BEGIN(nVersion), END(nNonce)); 
    }
    else    
    {
       return HashX17(BEGIN(nVersion), END(nNonce));    
    }
}


Also that is not possible:

CBlockIndex* pindexPrev = chainActive.Tip();
if (pindexPrev-&gt;nHeight &lt;= FORKX17_Main_Net)
As SajithP commented:


  modify the makefile to include the object of the class which has the chainActive as a member. e.g 'x.o' where chainActive is a member of class 'x'