Question

I have a class in which I would like to have a static member which is a struct.

for example:
.h file:

typedef struct _TransactionLog
{
    string Reference;
    vector<int> CreditLog;
    int id;
}TransactionLog;

class CTransactionLog {
    static TransactionLog logInfo;
public:
    static void Clear();
    static TransactionLog getLog();
};

.cpp file:

void CTransactionLog::Clear()
{
    logInfo.Reference = "";
    logInfo.CreditLog.clear();
 logInfo.id = 0;
}

TransactionLog CTransactionLog::getLog()
{
    return logInfo;
}

I get

Description Resource Path Location Type

undefined reference to `CTransactionLog::logInfo’ TransactionLog.cpp

Can someone please give me an example how to make this work? Having a static member which is a struct(with stl members), manipulate it with static member methods and include this header in few other parts of the code. This should be used to add logging through the application.

Answer 1

You need to initialize your static member in the cpp file:

//add the following line:
TransactionLog CTransactionLog::logInfo;

void CTransactionLog::Clear()
{
    logInfo.Reference = "";
    logInfo.CreditLog.clear();
 logInfo.id = 0;
}

TransactionLog CTransactionLog::getLog()
{
    return logInfo;
}