7.48.txt

Exercise 7.48: Assuming the Sales_data constructors are not explicit, what
operations happen during the following definitions

	string null_isbn("9-999-99999-9");
	Sales_data item1(null_isbn);
	Sales_data item2("9-999-99999-9");

What happens if the Sales_data constructors are explicit?

By Faisal Saadatmand

	string null_isbn("9-999-99999-9");

A C-style sting literal, i.e. of type const char *, is converted to the library
string object null_isbn.

	Sales_data item1(null_isbn);

Explicit conversion of library string null_isbn to Sales_data class-type: the
Sales_data string constructor creates an object item1 with members values:
"9-999-99999-9", 0, 0.

	Sales_data item2("9-999-99999-9");

Implicit conversion from a string literal to library string, in which a temp
string is created and passed to Sales_data string constructor. The constructor
then performs an explicit conversion from library string to Sales_data object
item2, same as the previous statement.

If the Sales_data constructors were explicit, the implicit conversion would
still take place since we are using DIRECT initializations as opposed to
copying (with =) and ONLY ONE class-type (implicit) conversion is taking place.