正则表达式口决：

正则其实也势利，削尖头来把钱揣； （指开始符号^和结尾符号$）

特殊符号认不了，弄个倒杠来引路； （指\. \*等特殊符号）

倒杠后面跟小w， 数字字母来表示； （\w跟数字字母 \d跟数字）

倒杠后面跟小d， 只有数字来表示；

倒杠后面跟小a， 报警符号嘀一声；

倒杠后面跟小b， 单词分界或退格；

-Regular fact, snobbish, and sharpened his head hides the money　(referring to the start symbols ^ and the end of the symbol $)

Special symbols recognized can not get down bars to lead the way　(referring to \ \* and other special symbols)

Down bars behind with small w, alphanumeric　(\ w with alphanumeric　\ d with numbers)

Down bar followed by a small d, only the figures to show that

Down the bar followed by a, and alarm symbol beep sound

Down bars followed by b, the word boundaries or backspace