4.34
-2.33333
5
20

##</code><code>##

4.34
-2.33333
0
5
0
5
12
0
0
0
20
4.3e+015

##</code><code>##

use Benchmark;

sub regexstuff() 
{ 
   map 
        {$foo =  $_ if /^-?(?=\d|\.\d)\d*\.?\d+$/} 
        (qw/4.34 -2.33333 abc 5 maurice 5_5_4_1 
          12peter peter12 shoe fred 20 4.3E15/); 
}

sub packstuffD()
{
   map 
        { $foo =  unpack ("d", pack ("d", $_)), "\n" }
        (qw/4.34 -2.33333 abc 5 maurice 5_5_4_1 12peter
          peter12 shoe fred 20 4.3E15/);
}

sub packstuffF()
{
   map 
        { $foo =  unpack ("f", pack ("f", $_)), "\n" }
        (qw/4.34 -2.33333 abc 5 maurice 5_5_4_1 12peter
          peter12 shoe fred 20 4.3E15/);
}

sub evalstuff()
{
   map 
        { eval{ local $^W = 1; $_ + 0 } } 
        (qw/4.34 -2.33333 abc 5 maurice 5_5_4_1 12peter
          peter12 shoe fred 20 4.3E15/);

    	if ( $@ ) 
       	{ 
           $result = "$invalue is *not* a Number; 
                Details: $@" 
        }
    	else
       	{ 
           $result = "$invalue appears to be a number."; 
        }
}

timethese ( 100000, 
   { packstuffD => "packstuffD", 
     regex => "regexstuff", 
     eval => "evalstuff", 
     packstuffF => "packstuffF" 
   } 
);
      eval: 13 wallclock secs (11.97 usr +  0.02 sys = 11.99 CPU) @ 8342.37/s (n=100000)
packstuffD: 11 wallclock secs (10.06 usr +  0.00 sys = 10.06 CPU) @ 9945.30/s (n=100000)
packstuffF: 10 wallclock secs (10.63 usr +  0.02 sys = 10.65 CPU) @ 9393.20/s (n=100000)
     regex: 11 wallclock secs (11.01 usr +  0.01 sys = 11.02 CPU) @ 9077.71/s (n=100000)