关于正则表达式的问题
我看到这个说法
$name = ereg_replace("[^A-Za-z0-9.]", "", $name);
[^A-Za-z0-9.] 和 [A-Za-z0-9.] 有什么区别？
根据我对正则表达式的理解，[]用于包含函数ereg_replace中替换的所有有效字符。
那么[]中包含^的目的是什么呢？
谢谢
I saw this statement
$name = ereg_replace("[^A-Za-z0-9.]", "", $name);
What is the difference between [^A-Za-z0-9.] and [A-Za-z0-9.]?
Based on my understanding of regular expression, the [] is used to include all valid characters for replacment in function ereg_replace.
Then what is the purpose of including ^ into the []?
Thank you
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字符类
[…]中的初始^反转字符类中描述的字符集。[A-Za-z0-9.]匹配A-Za-z0-9.描述的字符集中的一个字符，[^A- Za-z0-9.]匹配除A-Za-z0-9.描述的字符之一之外的任何其他字符。这些其他字符是什么取决于定义字符串的基本字符集。因此
[abc]匹配a、b或c和[^abc] 匹配除a、b和c之外的任何其他字符。您的示例代码将删除[A-Za-z0-9.]未描述的任何字符。这样就只剩下[A-Za-z0-9.]字符。The initial
^inside a character class[…]inverts the set of characters that are described inside the character class. While[A-Za-z0-9.]matches one character of the character set described byA-Za-z0-9.,[^A-Za-z0-9.]matches any other character except one of the characters described byA-Za-z0-9.. What these other characters are depends on the base character set the string is defined with.So
[abc]matches eithera,b, orcand[^abc]matches any other character excepta,b, andc. Your example code will remove any characters that are not described by[A-Za-z0-9.]. That leaves only characters of[A-Za-z0-9.].