(bison.info)Union Decl


Next: Type Decl Prev: Precedence Decl Up: Declarations

The Collection of Value Types
-----------------------------

   The `%union' declaration specifies the entire collection of possible
data types for semantic values.  The keyword `%union' is followed by a
pair of braces containing the same thing that goes inside a `union' in
C.

   For example:

     %union {
       double val;
       symrec *tptr;
     }

This says that the two alternative types are `double' and `symrec *'.
They are given names `val' and `tptr'; these names are used in the
`%token' and `%type' declarations to pick one of the types for a
terminal or nonterminal symbol (Note: Nonterminal Symbols.).

   Note that, unlike making a `union' declaration in C, you do not write
a semicolon after the closing brace.


automatically generated by info version 1.5

Dirfile and infopages generated Sat Dec 3 02:07:54 2005