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首位可以是字母以及下划线。
首位之后可以是字母，数字以及下划线。
下划线后不能接下划线（这个不知道怎么处理）。
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给一个 Perl 风格的结果，请大家验证一下是否正确：(^_([a-zA-Z0-9]_?)*$)|(^[a-zA-Z](_?[a-zA-Z0-9])*_?$)
Perl
(^_([a-zA-Z0-9]_?)*$)|(^[a-zA-Z](_?[a-zA-Z0-9])*_?$)
var flag = false; //用来判断 var reg = /^[a-zA-Z_]{1}[a-zA-Z\d_]*/; var str = '_ewfw_eq'; flag = reg.test(str); if (flag) { var reg1 = /__/; flag = !reg1.test(str); } console.log(flag);
$reg = '__sadsada';preg_match('/^([a-zA-Z0-9]|_[A-Za-z0-9])+w+/', $reg, $match);var_dump($match);exit;
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
给一个
Perl风格的结果，请大家验证一下是否正确：(^_([a-zA-Z0-9]_?)*$)|(^[a-zA-Z](_?[a-zA-Z0-9])*_?$)$reg = '__sadsada';
preg_match('/^([a-zA-Z0-9]|_[A-Za-z0-9])+w+/', $reg, $match);
var_dump($match);
exit;