cygwin,
$flex ch1-02.l
$gcc lex.yy.c -o ch1-02.exe
/cygdrive/d/Profiles/E6097C/LOCALS~1/Temp/ccFsaC7D.o:lex.yy.c:(.text+0x36c): und
efined reference to `_yywrap'
/cygdrive/d/Profiles/E6097C/LOCALS~1/Temp/ccFsaC7D.o:lex.yy.c:(.text+0xac1): und
efined reference to `_yywrap'
collect2: ld returned 1 exit status
solution: gcc lex.yy.c -o ch1-02.exe -lfl