Thread: [BeginnerQuestion]Why I compile lex.yy.c failed?

Wen Yi <chuxuec@outlook.com> writes:
> I am a beginner who are interested in database,when I do my study on the lex and yacc,I write a example.l like this:

> %%
> .\|n ECHO
> %%

> and then I generate a  lex.yy.c use lex
> but when I compile this file,something wrong happend:

> [beginnerc@bogon temp]$ flex '/home/beginnerc/work/temp/example.l'
> [beginnerc@bogon temp]$ cc lex.yy.c -o first -ll
> /home/beginnerc/work/temp/example.l: In function ¡®yylex¡¯:
> lex.yy.c:619:28: error: expected ¡®;¡¯ before ¡®break¡¯

I'm too lazy to actually go and read the flex manual right now,
but that error message suggests strongly that you need a semicolon:

.\|n ECHO;

This'd make sense since the action is supposed to be a C statement.

The universal style in Postgres' flex files is to write braces
around each action:

.\|n { ECHO; }

but I'm not sure that that's actually required, if your action is
only one C statement.  I suspect it's just making the action into
a valid C compound block.

            regards, tom lane