如何在正则表达式中写可选单词? [英] How to write optional word in Regular Expression?

问题描述

我想编写一个Java正则表达式来识别以下模式. abc def the ghi和abc def ghi

I want to write a java Regular expression that recognises the following patterns. abc def the ghi and abc def ghi

我尝试过:

abc def (the)? ghi

但是，它无法识别第二种模式.我哪里出错了?

But, it is not recognizing the second pattern.Where am I going wrong?

推荐答案

abc def (the )?ghi

           ^^

删除多余的space

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