Perhaps tr? 
$_ = "    \ta";
print tr/ \t/ \t/;
# prints "5"

[download]

Or count and delete: 

$_ = "    \ta";
print tr/ \t//d, $_;
# prints "5a"

[download]

In reply to Re: counting leading white spaces by hbm
in thread counting leading white spaces by Spooky

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