Create one negative DateInterval Object with DateTime

If you want to create one negative DateInterval, you may use the following ways

Get dateTime object two months ago.

$dateTime = (new DateTime());
var_dump($dateTime);

$month = -2;
$dateInterval = new DateInterval('P' . abs($month) . 'M');
 if ($month < 0) {
       $dateInterval->invert = 1;
 }
$dateTime->add($dateInterval);

it will shows:

object(DateTime)[94]
  public 'date' => string '2013-11-26 11:10:23' (length=19)
  public 'timezone_type' => int 3
  public 'timezone' => string 'Asia/Tokyo' (length=10)

object(DateTime)[94]
  public 'date' => string '2013-09-26 11:10:23' (length=19)
  public 'timezone_type' => int 3
  public 'timezone' => string 'Asia/Tokyo' (length=10)

count the appearance times of string in file

When you want to count the appearance lines of one special string in a file, you may use

grep -o will-fined-string  /path/to/file | wc -l

PHP goto keywords

goto has a bad reputation among programmers.

But sometime it is also very useful.

Here are one example
for($i=0,$j=50; $i<100 br="" i="">  while($j--) {
    if($j==17) goto end;
  } 
}
echo "i = $i";
end:
echo 'j hit 17';

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