operator double

Applies To
OField

Description
This method returns the object's value as a double.

Usage
operator double() const

Remarks
This method hands the value of the object back to the caller as a double. If the object's current value is not a double, the method attempts to convert the value. This can fail., resulting in a return of the value 0.0.

Return Value
The value of the field as a double; 0.0 on failure.

Example
Sum all the salaries of employees:

// open the employee database

ODatabase odb("ExampleDB", "scott", "tiger");

// open a dynaset on the employee's table

ODynaset odyn(odb, "select sal, comm from employees");

// get a field on the salary for speed

OField salf = odyn.GetField("sal");

By using the = operator in the declaration of salf we are invoking the copy constructor. It is copying the temporary object that is returned by the GetField method.

// sum the salaries

double sumsal = 0.0;

odyn.MoveFirst();

while (!odyn.IsEOF())

{

sumsal += (double) salf;

odyn.MoveNext();

}

// of course, we could have done the same thing (faster) with:

ODatabase odb("ExampleDB", "scott", "tiger");

ODynaset odyn(odb, "select sum(sal) from employees");

odyn.GetFieldValue(0, &sumsal);

// the server is good at that kind of bulk calculation

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