Question

[question update according to updated requirements]
I’ve implemented following function which should return either first not null element or throw an exception.
Also could you invent more classic and shorter name like ‘max’, ‘min’, ‘pair’?

template <typename T> T select_first_not_empty( const T& a, const T&b ) {     static T null = T();      if ( a == null && b == null )         throw std::runtime_error( 'null' );      return         a != null ? a : b; }  int main() {     const int a1 = 2;     const int b1 = 0;      const int* a2 = 0;     const int* b2 = new int(5);      const std::string a3 = '';     const std::string b3 = '';      std::cout << select_first_not_empty( a1, b1 ) << std::endl;     std::cout << select_first_not_empty( a2, b2 ) << std::endl;     std::cout << select_first_not_empty( a3, b3 ) << std::endl;      return 0; } 

Answer 1

you can try do next

template < typename T > T get_valuable( const T& firstValue,                  const T& alternateValue,                  const T& zerroValue = T() ) {     return firstValue != zerroValue ? firstValue : alternateValue; }  // usage char *str = 'Something'; // sometimes can be NULL std::string str2 ( get_valuable( str,  '' ) );  // your function template <typename T> T select_first_not_empty( const T& a,                            const T& b,                            const T& zerroValue = T() ) {     const T result = get_valuable( a, b, zerroValue );     if ( result == zerroValue )     {         throw std::runtime_error( 'null' );     }     return result; }