Bison Expression Parsing Failure c++ -

this bison parser code.

statement     : compound_statement     | expression_statement     ;    expression_statement     : ';'     | expression ';'                        {cout<<"expr found\n";}     ;  expression      : number_expression                    {cout << "number expression\n";}     ;  number_expression     : number_arith_expression               {cout << "arith expression\n";}     ;  number_arith_expression      : number_idenfiers     | number_constants     | number_arith_expression number_arith_expression '+'   { cout<<"found\n";}     | number_arith_expression number_arith_expression '-'   {}      ;  number_idenfiers     : ppnumvar                                                  {}     | ppsysnumvar                                               {}     ;  number_constants     : ppfloat                                                   {}     ; 

i gave expression

23 23 +;

my result :

found

arith expression

number expression

line number : 1 .. parse error

why doesn't parse @ expression_statment ? doesn't parse semicolon. should change work semicolon?

according grammar valid addition expression 2 expressions followed +, input has + in middle.