Template Example

The following code example shows the class template Array and its instantiations and the function template square and its instantiations.

In the following example:

• Array is a class template

• square is a function template

• Array<int> is a class template instantiation (template class)

• Array<int>::getlength is a member function of a template class

• square(int, int*) and square(double, double*) are function template instantiations (template functions)

  ---

   1		template<class C> void square(C num, C *result
   2		{
   3	 		*result = num * num;
   4		}
   5	
   6		template<class T> class Array
   7		{
   8		public:
   9	  		int getlength(void)
  10	 		{ 
  11	    			return length;
  12	  		}
  13	
  14	  		T & operator[](int i)
  15	  		{
  16	    			return array[i];
  17	 		}
  18	
  19	  		Array(int l)
  20	  		{ 
  21	    			length = l; 
  22	    			array = new T[length];
  23	  		} 
  24	  
  25	 	 	~Array(void)
  26	  		{ 
  27	   	 		delete [] array;
  28	  		} 
  29	
  30		private:  
  31	  		int length; 
  32	  		T *array; 
  33		}; 
  34	 
  

  ---

  ---

  35		int main(void)
  36		{ 
  37	  		int i, j = 3; 
  38	 		square(j, &i); 
  39	 
  40	 		double d, e = 4.1; 
  41	  		square(e, &d); 
  42	   
  43	  		Array<int> iarray(5); 
  44	  		for (i = 0; i < iarray.getlength(); ++i)
  45	  		{ 
  46	   			iarray[i] = i; 
  47	 		} 
  48	  
  49	  		Array<double> darray(5);     
  50	  		for (i = 0; i < iarray.getlength(); ++i)
  51	 		{  
  52	    			iarray[i] = i * 2.1;
  53	  		} 
  54	   
  55	  		return 0; 
  56		}
  

  ---