Regex on Splitting String - regex

Question

I am trying to split the following string into proper output using regex. Answers do not have to be in perl but in general regex is fine:
Username is required.
Multi-string name is optional
Followed by Uselessword is there but should be be parsed
Followed by an optional number
Following by an IP in brackets < > (Required)
String = username optional multistring name uselessword 45 <100.100.100.100>
Output should be:
Match 1 = username
Match 2 = optional multistring name
Match 3 = 45
Match 4 = 100.100.100.100

Answer 1

This sort of things are easier to handle using multiple regex. Here is an example:
my #arr = (
'username optional multistring name uselessword 45 <100.100.100.100>',
'username 45 <100.100.100.100>'
);
for(#arr){
## you can use anchor ^ $ here
if(/(\S+) (.+?) (\d+) <(.+?)>/){
print "$1\n$2\n$3\n$4\n";
}
## you can use anchor ^ $ here
elsif(/(\S+) (\d+) <(.+?)>/){
print "$1\n$2\n\n$3\n";
}
print "==========\n";
}
First if block is looking for four groups from the input. And the second block is looking for three groups.
If you need, you can use [ ]+ to handle multiple spaces between the groups.
Also, if you need, you can adjust the optional group (.+?) according to your preferred characters(usually through the character class [bla]).