regex in SCJP test

[tural ferhadov]

hello,
I am trying to solve an scjp test about regex.

here is a code...

import java.util.regex.*;

public class TestRegex{
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
java TestRegex "\d*" ab34ef
the answer is 01234456. I understood everything except the last output(6). Since the last index in "ab34ef" is 5, how is it possible to be printed 6 ?

Any help ....

[Nancy Avent]

tural ferhadov wrote:hello,
I am trying to solve an scjp test about regex.

here is a code...

import java.util.regex.*;

public class TestRegex{
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
java TestRegex "\d*" ab34ef
the answer is 01234456. I understood everything except the last output(6). Since the last index in "ab34ef" is 5, how is it possible to be printed 6 ?

Any help ....

Here is my try:
The expression "\d*" refers to any digit of length 0 or more; thus, it will match to all zero size matches too. The first match start before 'a' and end before 'a' (size zero match); this will print 0. What it means is the last match would be after 'f' (size zero match) and thus it will result in 6.

[Adam Crawford]

Take a look at this - I found this really useful when I was confused about the same thing.

Good luck!

[tural ferhadov]

Thank you guys, it really helped