Check if a sequence of numbers corresponds to a valid timestamp

Question

I need to check if a sequence matches a valid timestamp.
Use is_numeric, ctype_digit, will only validate if it is numerical... I want to know if the timestamp matches a date.

Answer 1

TL;DR

Use the class DateTime PHP and dates represented in a different format than UNIX timestamp to not have problems with dates.

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A UNIX timestamp is the number of seconds that have passed since the date 1970-01-01 00:00:00 in UTC.

Its limit is at most value that a 32-bit integer variable can support (-2147483648 to 2147483647), generating a date range between 1901-12-13 20:45:54 until 2038-01-19 03:14:07.

That is to say, today just check if the number is integer and is within that range.

But 2038 is coming soon, we’ll have a new "Millennium bug" ?

If we use date storage on Unix timestamps, yes, we will have application problems.

One solution to this problem is the use of 64-bit integers, which will make it possible to postpone this problem to the year 292277026596.

Today 64-bit PHP support is experimental (At least on Windows systems) and still nay supports 64-bit integers

In PHP, the best alternative is to use the class DateTime, where there is no such bug of the year 2038.

Answer 2

The following response is intended to complement the @gmsantos response.

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Using the class Datetime PHP as suggested by @gmsantos you achieve your goal.

However, for a validation, you have to:

• Use a Try...catch() block if you are programming with your Object-Oriented version
• Condition it with the boolean FALSE -OR- with the operator instanceof looking for an object Datetime, case using your procedural version date_create():

Object-Oriented

try {

    $dt = new DateTime( 1926036000 );

} catch( Exception $e ) {

    //die( $e -> getMessage() );

    die( 'Invalid date or timestamp' );
}

That’s because when the class builder Datetime fail it fires an Exception that can or needs (depending on the case) to be captured.

Note also that I left two ways to abort the operation. One with the error message sent by Datetime and other personalized.

The reason is because the exception message launched by Datetime is not very useful in production:

Datetime::__Construct(): Failed to parse time string (1926036000) at position 7 (0): Unexpected

Procedural

var_dump( date_create( 1926036000 ) instanceof DateTime ); // false

var_dump( date_create() instanceof DateTime ); // true

To validate check by FALSE can be more interesting by dispensing an assignment to a variable. If after validation the resulting object is used, prefer instanceof.

Although not demonstrated, when I say compare by FALSE I mean compare the data on the left with the operator !== ( $x !== FALSE ), since PHP recognizes several values as FALSE, including the zero that can be the return of the fragment below:

mktime( 21, 0, 0, 12, 31, 1969 ); // int 0

Even if it doesn’t make sense :P

[UPDATE]

As demonstrated by @gmsantos in the comments of this and another topic I made little giant mistake.

The error refers to me being setting the timestamp directly in the builder of Datetime what it’s not right. Strangely, for some timestamps "works", that is, the object is built but with a different result than expected, and for others not, shooting the Exception.

The correct is to use even the method Date::setTimestamp() after creating the object:

$dt = new DateTime;
$dt -> setTimestamp( 2147472001 );

var_dump( $dt );