在 PHP 中增加三个月的日期

The following should work, but you may need to change the format:

echo date('l F jS, Y (m-d-Y)', strtotime('+3 months', strtotime($DateToAdjust)));

Change it to this will give you the expected format:

$effectiveDate = date('Y-m-d', strtotime("+3 months", strtotime($effectiveDate)));

I assume by "didn't work" you mean that it's giving you a timestamp instead of the formatted date, because you were doing it correctly:

$effectiveDate = strtotime("+3 months", strtotime($effectiveDate)); // returns timestamp
echo date('Y-m-d',$effectiveDate); // formatted version

You need to convert the date into a readable value. You may use strftime() or date().

Try this:

$effectiveDate = strtotime("+3 months", strtotime($effectiveDate));
$effectiveDate = strftime ( '%Y-%m-%d' , $effectiveDate );
echo $effectiveDate;

This should work. I like using strftime better as it can be used for localization you might want to try it.

Tchoupi's answer can be made a tad less verbose by concatenating the argument for strtotime() as follows:

$effectiveDate = date('Y-m-d', strtotime($effectiveDate . "+3 months") );

(This relies on magic implementation details, but you can always go have a look at them if you're rightly mistrustful.)

The following should work,Please Try this:

$effectiveDate = strtotime("+1 months", strtotime(date("y-m-d")));
echo $time = date("y/m/d", $effectiveDate);

Following should work

$d = strtotime("+1 months",strtotime("2015-05-25"));
echo   date("Y-m-d",$d); // This will print **2015-06-25**

This answer is not exactly to this question. But I will add this since this question still searchable for how to add/deduct period from date.

$date = new DateTime('now');
$date->modify('+3 month'); // or you can use '-90 day' for deduct
$date = $date->format('Y-m-d h:i:s');
echo $date;

Add nth Days, months and years

$n = 2;
for ($i = 0; $i <= $n; $i++){
$d = strtotime("$i days");
$x = strtotime("$i month");
$y = strtotime("$i year");
echo "Dates : ".$dates = date('d M Y', "+$d days");
echo "<br>";
echo "Months : ".$months = date('M Y', "+$x months");
echo '<br>';
echo "Years : ".$years = date('Y', "+$y years");
echo '<br>';
}

public function getCurrentDate(){
return date("Y-m-d H:i:s");
}


public function getNextDateAfterMonth($date1,$monthNumber){
return date('Y-m-d H:i:s', strtotime("+".$monthNumber." months", strtotime($date1)));
}