正则表达式模式中的可选部分

Question

I have following strings to process

Name ( $4 USD )
Name ( $4.1 USD )
Name ( $4.12 USD )
Name ( $4123123.02 USD )

I want to USD amout from them Right now I a using follwoing regex pattern

Regex regex = new Regex(@"\( \$(?<cash>\d+\.\d{1,2}) USD \)");

but it does not match the first example. What should I change to make the .\\d{1,2} part optional? Thanks!

Answer 1

Regex regex = new Regex(@"\( \$(?<cash>\d+(?:\.\d{1,2})?) USD \)");

(?:...) is a non-capturing group, and the following ? makes that group optional.