Your test results:

print-1
In "/G(\d+)\s*kg\s*/ig" you're making exactly the same mistake as you did in your OP and which I pointed out in my initial response: "('G' should be '\G')". There is no 'G' to match!
print-2
In "/(\d+)\s*kg\s*/ig", you've used the 'g' modifier. It's repeatedly matching each number followed by the units (one after another). As you say: "this one does the job".
print-3
Your explaination of "/(\d+)\s*kg\s*/i" is correct.
"Please add some insight on what is the importance of \G and what are some practice usage scenario of \G?"

'\G' is not an assertion I use that much: I can't really give you an "I often find it useful for ..." type answer.

There's more information in "perlre: Assertions"; as well as links to additional, related documentation.

— Ken

In reply to Re^3: Regular expression by kcott
in thread Regular expression by pravakta

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