unable to regex certain pattern

Question

I am trying to write a regular expression with the following requirements:
(1) not allow #
(2) not allow &
(3) not allow \\t (tab)
(3) not allow multiple spaces (single space is ok)

Here is I tried:

^[^#&\t\s+]*$

However, I can't get my output as I want. What am I doing wrong?
Can someone help me?

Answer 1

This will work in many regex flavors (including PCRE and JavaScript):

^(?!.*  )[^#&\t]*$

First, do a negative look-ahead to make sure there aren't any double spaces, and then match zero or more characters that aren't # , & , or \\t .

Regex101 Tested

Answer 2

把任务分成所允许的字符的基本表现，再加上负先行停泊开始为“无双空格”断言：

^(?!.*  )[^#&\t]*$