[C++]Member functions are instantiated only when they are used

For class templates, member functions are instantiated only when they are used. This, of course, saves time and space.

   
     

    
      using
    
       
    
      namespace
    
       std;

template 
    
      <
    
      typename T
    
      >
    
      

    
      class
    
       myTemplate
{

    
      private
    
      :
 typename T m_t;

    
      public
    
      :
 myTemplate(T t):m_t(t){};
 T AddOne(){
 
    
      return
    
       m_t 
    
      +
    
       
    
      1
    
      ;
 }
 
    
      void
    
       Output(){cout
    
      <<
    
      m_t
    
      <<
    
      endl;}
};


    
      int
    
       main()
{
 myTemplate
    
      <
    
      int
    
      >
    
       i(
    
      10
    
      );
 i.AddOne();
 i.Output();
 myTemplate
    
      <
    
      string
    
      >
    
       s(
    
      "
    
      temp
    
      "
    
      );
 
    
      //
    
      s.AddOne(); 
    
      //
    
       Compile error becasue std::string has no operator + with int type
    
      

    
       s.Output(); 
    
      //
    
       however, this line has no issue
    
      

    
       
    
      return
    
       
    
      10
    
      ;
}