规则运算式可以做为与所要搜寻之文字进行比较的字元模式。
The regular expression serves as character pattern to compare with the text being searched.
编译器在下列注解中找不到常用模式，因为第三列的第二个字元不是星号。
The compiler finds no common pattern in the following comment because the second character on the third line is not an asterisk.
新字元可能无法附加到搜寻模式。
New characters may not be appended to a failed search pattern.
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