lex/yacc won't recognize a string (syntax error) - lex

Question

Hi i'm trying to let lex/yacc split this string
table subwayLines:int[3]
into tokens of table, subwayLines, int[3] with the [3] optional(i.e. int or int[3])
everything is fine until i try to recognize the "int",
so this is what i did in lex
[A-Za-z0-9\[\]]+ { /* column property*/
yylval.sval = (char *)strdup(yytext);
char* temp=yylval.sval;
return STRING;
}
i know the problem is in
[A-Za-z0-9\[\]]+
because when i changed it to
[A-Za-z]+("[")?+[0-9]+("]")?+(",")?
it works except I still can't go without the "[" or "]", for example, if i wrote this in my string:
table subwayLines:int
then it gives me a syntax error
so does anyone knows how to do change it? thanks

Answer 1

To make the [3] optional, this will not work:
[A-Za-z]+("[")?+[0-9]+("]")?+(",")?
You've made only the square brackets optional, but not the number in between. You need something like
[A-Za-z]+("["[0-9]+"]")?
I.e. the entire square-bracketed part is optional.
Also the combination (REGEX)?+ doesn't make much sense (the ?+ part of it). It's equivalent to (REGEX)*, since you're effectively saying that (REGEX) is optional, one or more times, which is like zero or more.
(Not sure why you have the optional comma in the second example; the first one doesn't recognize a comma and it's not shown in your example input.)