php current time greater than timestamp gives false result - php

Question

Can't figure out why the following returns false:
$timestamp = '1535552942';
if (time() <= strtotime((int)$timestamp + 10))) // time() = 1535553866
The current time IS greater than the timestamp + 10 s!!! I've checked in logs!
What's wrong with this?

Answer 1

Quoting the docs:
strtotime
Parse about any English textual datetime description into a Unix timestamp
In other words, you pass something that makes sense in English into this function - and expect timestamp as a result.
Instead you pass timestamp into the function, and strtotime just fails to get what you want from it. For example, this online demo shows int(31009790155) as result of strtotime((int)$timestamp + 10)) - which is in the future far far away.
Perhaps you meant it to be implemented this way:
$timestamp = '1535552942';
if ( time() <= strtotime('+10 seconds', $timestamp) ) { ... }
... but actually I fail to see why you can't just add 10 (as a number) to timestamp and then compare it against time() directly. These are the numbers, in the end.

Answer 2

According to the official website of PHP, the definition of function strtotime is....
strtotime
Parse about any English textual datetime description into
a Unix timestamp
What this definition says that you can provide Only English textual datetime. And you are providing it an Integer whereas this strtotime is looking for English textual.
When you will print return value of strtotime it will show your current timestamp.
$timestamp = 'now';
echo strtotime($timestamp);
But when you will try to print its return value with an integer argument, then it will nothing, as given below...
$timestamp = 1535552942;
echo strtotime($timestamp);
Because this function return timestamp on success otherwise return false.
When you will provide it English textual value and try to add one in argument, it will generate a warning...
$timestamp = 'now';
echo strtotime($timestamp+1);
Warning: A non-numeric value encountered in
Because, according to the PHP generates errors or warning on arithmetics with invalid strings.
New E_WARNING and E_NOTICE errors have been introduced when invalid
strings are coerced using operators expecting numbers or their assignment equivalents. An E_NOTICE is emitted when the string begins with a numeric value but contains trailing
non-numeric characters, and an E_WARNING is emitted when the string
does not contain a numeric value.
Whereas above-given snippet fulfill this condition.
So, now just change your value of $timestamp to "now" or any other valid English textual and remove int from your if condition, then it will work perfectly.
$timestamp = "now";
if (time() <= strtotime($timestamp)){
echo "it works";
}