Обсуждение: where can I find the source code of functions?

Dear all,
   Where can I find the source code of  ODBC functions in pgsql(somthing like the RIGHT(),LEFT())?   And also the
sourcecode of database functions( substr()..etc..)? I have download the 7.2.src.rpm   but I can't find them...
 

Best Regards'
Dean Lu