接受0.5和整数的正则表达式

Question

Hi I need help on a regular expression which accepts only 0.5 and whole numbers. I try this but its not working: pattern="^[0.5][0-9]*"

Can someone help me? Thanks

Answer 1

Something like the following: ^0\\.5|\\d+$ . Just pay attention that in Java code you have to write duplicate back slashes, ie Pattern.compile("0\\\\.5|\\\\d+$") .

Back slash before . is required to make regex to understand that it is the character . and not "any character"