请教一个正则表达式的基础知识。-PHP Tutorial-php.cn

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请教一个正则表达式的基础知识。

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Jun 20, 2016 pm 12:41 PM

不知道这个问题应该在哪问，就借宝地请教一下。
刚才看到一个例子，有三组字符如下:
z
zo
zoo
为什么zo*可以匹配z呢？zo+就只能匹配zo,zoo
难道zo*等于z{1}o*？
新手刚开始学正则，很多地方还不太明白，还请高手给予指点，谢谢。

回复讨论(解决方案)

*表示匹配前面的字符零次或多次，+表示一次或多次
zo*表示z后面有零个或多个o，zo+表示zo后面有零个或多个o

为什么zo*可以匹配z呢？zo+就只能匹配zo,zoo
*表示匹配0次或多次

所以zo* 匹配 z后面0个o到N个o都可以
z
zo
zoo
zoooo...都可以

如果你要匹配至少一次
应该写zo+

谢谢楼上两位。
*和+的意思我明白，我只是不明白他们的影响范围。根据你们的解答，看来*和+只会影响到o而对z没有影响。我之前一直以为zo*是指有0或N个zo，那看来我理解错了，zo*应该是指有1个z，0或N个o，应该是这样吧？

嗯，你现在的理解是对的了

0或N个zo 应该这样写 (zo)*

为什么zo*可以匹配z呢？
zo* 表示一个 z 和 0 到 n 个 o 这样的字符组合

正则表达式的匹配单位是字符，而不是单词

谢谢大家，现在彻底清楚了。

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