quantifiers

[rakhee gupta]

Hi, I was going through K&B chapter-6 the following question:

Given:
import java.util.regex.*;
class Regex2 {
public static void main(String[] args) {
Pattern p = Pattern.compile(args[0]);
Matcher m = p.matcher(args[1]);
boolean b = false;
while(b = m.find()) {
System.out.print(m.start() + m.group());
}
}
}
And the command line:
java Regex2 "\d*" ab34ef
What is the result?
A. 234
B. 334
C. 2334
D. 0123456
E. 01234456
F. 12334567
G. Compilation fails.

The answer to this question is : E.
Till 0123445 its clear to me but after that where this digit 6 is coming from because index 6 is not there in the input string.

Thanks

[marc weber]

See our SCJP FAQ: Could someone explain the Regex2 class from K&B's Java 5 Study Guide?

[Keith Nagle]

It does seem a little confusing but I read this article from sun (regex) and it
helped me understand. What helped me nail it, was by practicing with some code examples. Copy the code from the sun article and play around with some patterns and input strings. I guarantee you will get the hang of it if you do!
Best of luck

Have a look at the above link I posted and then check this out!
http://java.sun.com/docs/books/tutorial/essential/regex/quant.html
[ July 24, 2008: Message edited by: Keith Nagle ]