c_cpp 编程练习

Posted 2021-05-14

#!/usr/bin/env python

strings = ['foobarbaz', 'a', '', 'this is a test']

reversed = [str[::-1] for str in strings]

print reversed

#!/usr/bin/env perl

use warnings;
use strict;

my @strings = qw(foobarbaz f 123);

foreach (@strings) {
    print strrev($_) . "\n";
}

sub strrev {
    my $str = shift;
    my @chars = split('', $str);
    my $rev = join('', reverse(@chars));
    return $rev;
}

#!/usr/bin/env php
<?php
$strings = array(
    'foo bar baz',
    '',
    'a',
    'quickfox',
);

foreach ($strings as $str) {
    echo _strrev($str) . "\n";
}

function _strrev($str)
{
    $rev = '';

    $i = strlen($str);
    while ($i > 0) {
        $rev .= $str[$i-1];
        $i--;
    }

    return $rev;
}

#include <stdio.h>

int main()
{
    /**
     * 0b01111111000000000000000000000001
     * 2130706433
     * 0x7f000001
     * 127.0.0.1
     */
    int ip = 2130706433;
    char *p = NULL;

    p = (char *)&ip;
    printf("dotted quad: %d.%d.%d.%d => %d\n", p[3], p[2], p[1], p[0], ip);

    return 0;
}

#!/usr/bin/env perl
#
# when will baz($arr, 0, 0) == true ?
#

use strict;
use warnings;

my $arr = [
    [0, 0, 0, 1, 1, 1, 0, 0, 0, 0],
    [0, 1, 0, 1, 1, 0, 1, 0, 0, 0],
    [2, 1, 0, 0, 0, 0, 1, 0, 0, 0],
    [0, 3, 0, 0, 0, 0, 3, 0, 0, 7],
    [0, 1, 0, 1, 0, 0, 0, 0, 0, 0],
    [1, 0, 0, 0, 0, 0, 1, 0, 0, 0],
    [2, 0, 1, 0, 0, 0, 0, 0, 9, 9],
    [2, 0, 2, 1, 0, 0, 2, 0, 0, 0],
    [4, 0, 3, 0, 0, 0, 0, 0, 0, 0],
    [5, 0, 0, 0, 0, 0, 1, 0, 0, 0],
];

if (baz($arr, 0, 0)) {
    print "baz() => True\n";
}

sub baz {
    my ($arr, $x, $y) = @_;

    my $result;

    my $count = 0;
    for (my $i = 0; $i < 10; $i++) {
        if ($$arr[$i][$x] == 0) {
            $count++;
        }
    }
    $result = ($count == 10);

    $count = 0;
    for (my $i = 0; $i < 10; $i++) {
        if ($$arr[$y][$i] == 0) {
            $count++;
        }
    }

    return ($result || ($count == 10));
}

/**
 * long2ip
 */
#include <stdio.h>

int main()
{
	int ip = 0b01111111000000000000000000000001; // dotted-quad 127.0.0.1 (for visualizing)
	int a, b, c, d;
	int mask = 0xFF;

	a = (ip >> 24) & mask;
	b = (ip >> 16) & mask;
	c = (ip >> 8) & mask;
	d = ip & mask;

	printf("dotted quad: %d.%d.%d.%d\n", a, b, c, d);

	return 0;
}