parsing - Shift/reduce conflicts in bison -

i'm new bison , i'm having trouble shift/reduce conflicts... i'm trying load file array data[]:

struct  _data {   char name[50];    char surname[50];    int year; } data[1000]; 

here part of bison code:

%token id num nl eof   %%  file   : list eof        ; list   : record        | list record        ; record : name surname year nl  { count++; }        | nl                    { count++; }        | /*empty*/        ; name   : id                    { strcpy(data[count].name, yytext); }        ; surname: id                    { strcpy(data[count].surname, yytext); }        ; year   : num                   { data[count].year= atoi(yytext); }        ;  %%             

i error:

conflicts: 5 shift/reduce 

any idea went wrong?

you can use -v option bison produce .output file containing lot more information can diagnose shift/reduce conflicts. in particular, show every parser state, including list of items, , indicate states have conflicts.

but in case, problem pretty simple. stripped essentials have:

list: record     | list record     ;  record:       | /* nothing */       ; 

ignoring definition of something is, problem list can consist of number of records, 1 after another, , record can empty. means nothing can parsed number of empty records, totally ambiguous. 2 consecutive somethings in input separated 0, 1, 2, 42, or 273 empty records. since parser can't know whether start parsing new something (shift) or emit empty record (reduce), complains there shift/reduce conflict.

in case solution pretty simple. can see non-empty something must end nl; presumably intent file consists of number of records, each on own line. can rewrite:

file:    list eof     ;  list:    record     |    list nl record     ;  record:  name surname year       |  /* empty */       ; 

now record, empty or not, must followed either eof or nl. cannot directly followed record.