Templates
Templates are also called 'generics' or 'parameterized types'. Programming with templates is called generic programming.
In general, study of templates can be divided in two parts.
1) Function templates
2) Class templates
Function Templates
Function templates enable us to construct a family of related functions. Suppose we want to have function add ( ), which adds two numbers. C++ is strongly typed. Hence if we define add ( int, int ) it will not work properly for floats or complex numbers. Here the concept of template can be brought in. We will define function add to have parameters of type T, where T is template type.
For Example,
template < class T >
void add ( T a, T b ) ;
The first line tells the compiler that we are using a generic type T. Once T is accepted as some type, declaration of the function is logical. While defining the function, syntax of C++ requires us to add template < class T > before the function definition. Now a function add ( ) can be called with parameters of any type.
Let us study a simple program to study function templates.
#include < iostream.h >
template < class T >
void add ( T a, T b ) ;
int main ( )
{
int a = 5, b = 7 ;
add ( a, b ) ;
float x = 1.5, y = 2.4 ;
add ( x, y ) ;
return 0 ;
}
template < class T >
void add ( T a, T b )
{
cout << a + b <<"\n" ;
}
output
12
3.9