ビットシフト

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ビットシフト

C

#include <stdio.h>
int count_bits(unsigned x)

{

    int count = 0;

    while (x)

    {

        if (x & 1u) count++;

        x >>= 1;

    }

    return count;

}
int int_bits(void)

{

    return count_bits(~0u);

}
void print_bits(unsigned x)

{

    int i;

    for (i = int_bits() - 1; i >= 0; i--)

        putchar(((x >> i) & 1u) ? '1' : '0');
    putchar('\n');

}
int main(int argc, char* argv[])

{

    unsigned na = 12345;
    printf("A       = ");  print_bits(na);

    printf("A >> 1  = ");  print_bits(na >> 1);

    printf("A >> 2  = ");  print_bits(na >> 2);

    printf("A >> 3  = ");  print_bits(na >> 3);

    printf("A >> 4  = ");  print_bits(na >> 4);

    putchar('\n');
    printf("A       = ");  print_bits(na);

    printf("A << 1  = ");  print_bits(na << 1);

    printf("A << 2  = ");  print_bits(na << 2);

    printf("A << 3  = ");  print_bits(na << 3);

    printf("A << 4  = ");  print_bits(na << 4);
    return 0;

}

実行結果

R:\>lesson057\project1.exe

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

Delphi

program Project1;
{$APPTYPE CONSOLE}
uses

    SysUtils;
function count_bits(x:Longword):Integer;

var

    count:Integer;

begin

    count := 0;

    while (x <> 0) do

    begin

        if x and 1 <> 0 then inc(count);

        x := x shr 1;

    end;

    result := count;

end;
function int_bits():Integer;

begin

    result := count_bits(Longword(not 0));

end;
procedure print_bits(x:Longword);

var

    i: Integer;

begin

    for i := int_bits() - 1 downto 0 do

    begin

        if x shr i and 1 <> 0 then

            write('1')

        else

            write('0');

    end;
    writeln('');

end;
procedure main();

var

    na: Longword;

begin

    na := 12345;

    write('A       = '); print_bits(na);

    write('A >> 1  = '); print_bits(na shr 1);

    write('A >> 2  = '); print_bits(na shr 2);

    write('A >> 3  = '); print_bits(na shr 3);

    write('A >> 4  = '); print_bits(na shr 4);

    writeln('');
    write('A       = '); print_bits(na);

    write('A << 1  = '); print_bits(na shl 1);

    write('A << 2  = '); print_bits(na shl 2);

    write('A << 3  = '); print_bits(na shl 3);

    write('A << 4  = '); print_bits(na shl 4);

end;
begin

    main;

end.

実行結果

S:\>lesson057\project1.exe

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

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

Ruby

def count_bits(x)
    count = 0
    while (x != 0)
        count += 1 if (x & 1 != 0) 
        x = (x >> 1) & ~(~0 << (x.size * 8))
    end
    return count
end

def int_bits
    return count_bits(~0)
end

def print_bits(x)
    (int_bits - 1).downto(0) do |i|
        print(((x >> i) & 1) != 0 ? '1' : '0')
    end

    puts ""
end

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)
puts  ""

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:\>ruby  l:\lesson_07_057.rb

A       = 000000000000000000011000000111001

A >> 1  = 000000000000000000001100000011100

A >> 2  = 000000000000000000000110000001110

A >> 3  = 000000000000000000000011000000111

A >> 4  = 000000000000000000000001100000011
A       = 000000000000000000011000000111001

A << 1  = 000000000000000000110000001110010

A << 2  = 000000000000000001100000011100100

A << 3  = 000000000000000011000000111001000

A << 4  = 000000000000000110000001110010000