ビットシフト

明解Ｃ言語 入門編 > 7. 基本型 >

ビットシフト

Perl

sub count_bits
{
    my ($x) = @_;
    $count = 0;
    while ($x)
    {
        $count++ if ($x & 1) ;
        $x >>= 1;
    }
    return $count;
}

sub int_bits
{
    return &count_bits(~0);
}

sub print_bits
{
    my ($x) = @_;
    for ($i = &int_bits - 1; $i >= 0; $i--)
    {
        print ((($x >> $i) & 1) ? '1' : '0');
    }

    print "\n";
}

$na = 12345;

print "A       = ";  &print_bits($na);
print "A >> 1  = ";  &print_bits($na >> 1);
print "A >> 2  = ";  &print_bits($na >> 2);
print "A >> 3  = ";  &print_bits($na >> 3);
print "A >> 4  = ";  &print_bits($na >> 4);
print "\n";

print "A       = ";  &print_bits($na);
print "A << 1  = ";  &print_bits($na << 1);
print "A << 2  = ";  &print_bits($na << 2);
print "A << 3  = ";  &print_bits($na << 3);
print "A << 4  = ";  &print_bits($na << 4);

実行結果

L:\>perl lesson_07_057.pl

A       = 00000000000000000011000000111001

A >> 1  = 00000000000000000001100000011100

A >> 2  = 00000000000000000000110000001110

A >> 3  = 00000000000000000000011000000111

A >> 4  = 00000000000000000000001100000011
A       = 00000000000000000011000000111001

A << 1  = 00000000000000000110000001110010

A << 2  = 00000000000000001100000011100100

A << 3  = 00000000000000011000000111001000

A << 4  = 00000000000000110000001110010000