当您事先知道搜寻字串时，请使用语法2。

Use Syntax 2 when you know the search string ahead of time.

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传回字元位置，代表搜寻字串中第一个符合的位置。

Returns the character position where the first successful match begins in a searched string.

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最简单的规则运算式形式，就是与搜寻字串比较的单一、一般字元。

The simplest form of a regular expression is a single, ordinary character that is compared with a searched string.

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