Question

求一个正则，必须同时有字母,数字,下划线，长度6到18位？

Answer 1

^(?=.*_)(?=.*\d)(?=.*[a-zA-Z]).{6,18}$
"同时有"麻烦了点, 不过总算写出来了

Answer 2

[a-zA-Z_0-9]{6,18}

Answer 3

nishizhu_001

追问

什么呀？