Class Templates
Templates allow us to define generic classes. It is used to define a pattern for class definitions. Alternatively we could call it a parameterized class. Here, there will be one class definition, which will produce many classes depending on the parameter we specify in terms of template definition.
The general format of a class template is :
template < class T >
class classname
{
// . . .
// class member specification
// with type T whereever appropriate
// . . .
} ;
Note that the class template definition is very similar to an ordinary class definition except the prefix template < class T > and the use of type T. This prefix tells the compiler that we are going to declare a template and use T as a type name in the declaration.
Assume that we want to define a Vector class with the data type as a parameter and then use this class to create a vector of any data type instead of defining a new class every time. The template mechanism enables us to achieve this goal.
template < class T >
class vector
{
T a [ 10 ] ;
public :
// . . .
// . . .
} ;
Thus, vector has become a parameterized class with the type T as its parameter. T may be substituted by any data type including the user-defined types. Now, we can create vectors for holding different data types.
For Example,
vector < int > object1 ; // 10 element int vector
vector < float > object2 ; // 10 element float vector