Capturing the zero-or-more-spaces surrounding the equals symbol is NOT helpful... and means OP, were your suggestion adopted, would have to use $3 for the value of width.

Moreover, if there were zero-digits after the equals symbol, the data would not match OP's explicit example and implicit spec.

Update re ckj's update which is MOSTLY WRONG. Reread the above.

(\d+) captures one or more digits. (\d*) matches ZERO digits which is useless.

perl -e "use 5.014; my $foo= 'bc'; if ($foo = /(\d*)/ ) {say 'match'; 
+}else{ say 'Duh!';}"
match
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OP does not ask to capture the spaces. There is no need to capture the spaces to account for their quantity; 0, 1, 2 or whatever.
Your parens are capturing. Grouping (aka 'non-capturing') parens are (?:...).

Nothing was said about print.
And "not helpful" ne "not match."

Please read carefully before unburdening yourself of mis-statements.

Despite it's irrelevance here, though, you did get one aspect of your reply partially right: "TIMTOWTDI." But -- as the rest of that wisdom goes - 'and most of them are wrong.'

</Update>