D语言结构初始化

import std.stdio;

struct Books { 
   char [] title; 
   char [] subject = "Empty".dup; 
   int   book_id = -1; 
   char [] author = "Raj".dup;  
}; 

void main( ) { 
   Books Book1 = Books("D Programming".dup, "D Programming Tutorial".dup, 6495407 ); 
   printBook( Book1 ); 

   Books Book2 = Books("D Programming".dup, 
      "D Programming Tutorial".dup, 6495407,"Raj".dup ); 
   printBook( Book2 );

   Books Book3 =  {title:"Obj C programming".dup, book_id : 1001};
   printBook( Book3 ); 
}

void printBook( Books book ) { 
   writeln( "Book title : ", book.title); 
   writeln( "Book author : ", book.author); 
   writeln( "Book subject : ", book.subject); 
   writeln( "Book book_id : ", book.book_id); 
}