in reply to first 5 bits and last 3 bits

Use bitmask and bitwise boolean operations. 
fisher% perl -e 'my $byte=129; my $first5=$byte&0xf8; printf "%08b, %d
+\n", $byte, $first5;'
10000001, 128

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Re^2: first 5 bits and last 3 bits
by DrHyde (Prior) on Jul 27, 2011 at 09:26 UTC
    If you're creating a bitmask, it's clearer to say 0b11111000 than 0xf8.
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