将中缀表达式转换为后缀表达式，并计算任意四则运算表达式的结果，采用链表和队列实现，非文法和状态机-Infix expression would be converted to suffix expressions, and calculate the arithmetic expression of arbitrary results, the use of linked lists and queues to achieve, non-grammar and the state machine
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001422s ]
SELECT `a`.`aid`,`a`.`title`,`a`.`create_time`,`m`.`username` FROM `jrk_downrecords` `a` INNER JOIN `jrk_member` `m` ON `a`.`uid`=`m`.`id` WHERE `a`.`status` = 1 GROUP BY `a`.`aid` ORDER BY `a`.`create_time` DESC LIMIT 10 [ RunTime:0.139792s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001453s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.003424s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001682s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.006484s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.001620s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003345s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.015983s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001350s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 190927 [ RunTime:0.001417s ]
