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PHP Date Exercises : Get the first and last day of a month from a specified date

PHP date: Exercise-8 with Solution

Write a PHP script to get the first and last day of a month from a specified date.

Sample Solution:

PHP Code:

<?php
$dt = "2008-02-23";
echo 'First day : '. date("Y-m-01", strtotime($dt)).' - Last day : '. date("Y-m-t", strtotime($dt)); 
?>

Sample Output:

First day : 2008-02-01 - Last day : 2008-02-29

Flowchart :

Flowchart: Get the first and last day of a month from a specified date

PHP Code Editor:

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PHP: Tips of the Day

PHP represents "no value" with the null keyword. It's somewhat similar to the null pointer in C-language and to the NULL value in SQL.

Setting the variable to null:

Example:

$nullvar = null; // directly
function doSomething() {} // this function does not return anything
$nullvar = doSomething(); // so the null is assigned to $nullvar

Checking if the variable was set to null:

if (is_null($nullvar)) { /* variable is null */ }
if ($nullvar === null) { /* variable is null */ }

Null vs undefined variable

If the variable was not defined or was unset then any tests against the null will be successful but they will also generate a Notice: Undefined variable: nullvar:

$nullvar = null;
unset($nullvar);
if ($nullvar === null) { /* true but also a Notice is printed */ }
if (is_null($nullvar)) { /* true but also a Notice is printed */ }

Therefore undefined values must be checked with isset:

if (!isset($nullvar)) { /* variable is null or is not even defined */ }