The difference with pure virtual fuction and virtual fuction

virtual fuction:

class WageEmployee
{
public:
  virtual float computePay();
};

class SalesPerson : public WageEmployee
{
public:
  float computePay();
};

    A virtual function is a member function that you expect to be redefined in derived classes.  When you refer to a derived class object using a pointer or a reference to the base class, you can call a virtual function for that object and execute the derived class's version of the function.

pure virtual fuction:

class WageEmployee
{
public:
  virtual float computePay() = 0;
};

class SalesPerson : public WageEmployee
{
public:
  float computePay();
};

the difference  is
1.
if a class have a pure virtual fuction ,the the class is a abstract class
can't instance.
but contain virtual fuction can instance