class member initialization?

[punchinello]

class HRException
{
public:
    HRException() :
         m_pMessage("") {}
    virtual ~HRException() {}
    HRException(const char *pMessage) :
         m_pMessage(pMessage) {}
    const char * what() { return m_pMessage; }
private:
    const char *m_pMessage;
};

It's a definition of an exception class I guess. How does the colon and the following "m_pMessage("")" work? Why does it have to be innitialized in this fashion? Thank you very much in advance!

[mike_2000_17]

The things between the colon and the curly brace is called the "initialization list". Read this faq on constructors for a good explanation on why this is preferable to assignments inside the body of the constructor.

[punchinello]

Thank you very much!