Hello everybody.
I am learning Java Regular expression. But I got a problem, I am not able to understand the use of underscore.
I have an expression say :
Pattern.compile("[a-zA-Z]+[_1-9a-zA-Z]*")
This means [a-zA-Z] one or more times, but what does [_1-9a-zA-Z] means? The last '*' implies the occurrence of [_1-9a-zA-Z] will be zero or more time. What is the use of underscore here? Thank you.