如何使用 PHP 查找一个月中的第一个日期和最后一个日期？

小开

This will give you the last day of the month:

function lastday($month = '', $year = '') {
if (empty($month)) {
$month = date('m');
}
if (empty($year)) {
$year = date('Y');
}
$result = strtotime("{$year}-{$month}-01");
$result = strtotime('-1 second', strtotime('+1 month', $result));
return date('Y-m-d', $result);
}

And the first Day:

function firstDay($month = '', $year = '')
{
if (empty($month)) {
$month = date('m');
}
if (empty($year)) {
$year = date('Y');
}
$result = strtotime("{$year}-{$month}-01");
return date('Y-m-d', $result);
}

小开

You can use the date function to find how many days in a month there are.

// Get the timestamp for the date/month in question.
$ts = strtotime('April 2010');


echo date('t', $ts);
// Result: 30, therefore, April 30, 2010 is the last day of that month.

Hope that helps.

EDIT: After reading Luis' answer, it occurred to me you may want it in the right format (YY-mm-dd). It may be obvious, but doesn't hurt to mention:

// After the above code
echo date('Y-m-t', $ts);

小开

最佳答案

The easiest way is to use date, which lets you mix hard-coded values with ones extracted from a timestamp. If you don't give a timestamp, it assumes the current date and time.

// Current timestamp is assumed, so these find first and last day of THIS month
$first_day_this_month = date('m-01-Y'); // hard-coded '01' for first day
$last_day_this_month  = date('m-t-Y');


// With timestamp, this gets last day of April 2010
$last_day_april_2010 = date('m-t-Y', strtotime('April 21, 2010'));

date() searches the string it's given, like 'm-t-Y', for specific symbols, and it replaces them with values from its timestamp. So we can use those symbols to extract the values and formatting that we want from the timestamp. In the examples above:

Y gives you the 4-digit year from the timestamp ('2010')
m gives you the numeric month from the timestamp, with a leading zero ('04')
t gives you the number of days in the timestamp's month ('30')

You can be creative with this. For example, to get the first and last second of a month:

$timestamp    = strtotime('February 2012');
$first_second = date('m-01-Y 00:00:00', $timestamp);
$last_second  = date('m-t-Y 12:59:59', $timestamp); // A leap year!

See http://php.net/manual/en/function.date.php for other symbols and more details.

小开

Simple one

Y - A full numeric representation of a year, 4 digits
m - Numeric representation of a month, with leading zeros
t - Number of days in the given month

Reference - http://www.php.net/manual/en/function.date.php

<?php
echo 'First Date    = ' . date('Y-m-01') . '<br />';
echo 'Last Date     = ' . date('Y-m-t')  . '<br />';
?>

小开

To get the first and last date of Last Month;

$dateBegin = strtotime("first day of last month");
$dateEnd = strtotime("last day of last month");


echo date("D-F-Y", $dateBegin);
echo "<br>";
echo date("D-F-Y", $dateEnd);

小开

For specific month and year use date() as natural language as following

$first_date = date('d-m-Y',strtotime('first day of april 2010'));
$last_date = date('d-m-Y',strtotime('last day of april 2010'));
// Isn't it simple way?

but for Current month

$first_date = date('d-m-Y',strtotime('first day of this month'));
$last_date = date('d-m-Y',strtotime('last day of this month'));

小开

$month=01;
$year=2015;
$num = cal_days_in_month(CAL_GREGORIAN, $month, $year);
echo $num;

display 31 last day of date

小开

If you want to find the first day and last day from the specified date variable then you can do this like below:

$date    =    '2012-02-12';//your given date


$first_date_find = strtotime(date("Y-m-d", strtotime($date)) . ", first day of this month");
echo $first_date = date("Y-m-d",$first_date_find);


$last_date_find = strtotime(date("Y-m-d", strtotime($date)) . ", last day of this month");
echo $last_date = date("Y-m-d",$last_date_find);

For the current date just simple use this

$first_date = date('Y-m-d',strtotime('first day of this month'));
$last_date = date('Y-m-d',strtotime('last day of this month'));

小开

In simple format

   $curMonth = date('F');
$curYear  = date('Y');
$timestamp    = strtotime($curMonth.' '.$curYear);
$first_second = date('Y-m-01 00:00:00', $timestamp);
$last_second  = date('Y-m-t 12:59:59', $timestamp);

For next month change $curMonth to $curMonth = date('F',strtotime("+1 months"));

小开

You can use DateTimeImmutable::modify() :


$date = DateTimeImmutable::createFromFormat('Y-m-d', '2021-02-13');


var_dump($date->modify('first day of this month')->format('Y-m-d')); // string(10) "2021-02-01"
var_dump($date->modify('last day of this month')->format('Y-m-d')); // string(10) "2021-02-28"

小开

For those asking in the mysql context, if you have a $dateFrom like '2022-07-02' and want the first date, do this

date('Y-m-01', strtotime( $dateFrom))

You can do similar things for last date etc.