What is the difference between “a{1}” and “a” in regex?

Question

Some string was matched with the following `regex

([0-9]\s+){1}

Why did author use {1} in the end of regex?

Can I safely remove it?

Answer 1

Yes, there is no difference at all. Possibly it was left over from tweaks made while the regex was being built and tested.

Answer 2

在您的示例中， {1}将正则表达式匹配限制为仅一个整数或空格。

Answer 3

It is probably a leftover from debugging/writing the query when the author experimented with {1,2} or so.

Yes, you can remove it.

Answer 4

if it is the result of an interpreted code (log/debug coming from script for exemple) the 1 could be the value of a variable. If it is directly in a script, {1} is the default behavior so it is the same (but take longer to work due to extra interpreation to make by the parser)