time()

[sungpeng]

$timestamp = time();
echo "$timestamp";

result "1321422809";

 

What does 1321422809 stand for?

[sungpeng]

I can't understand the function of $timestamp in date also

 

date("w",$timestamp=time());

 

[Drummin]

From what I understand, a timestamp is the number of seconds from January 1, 1970 at 00:00.  I personally don't find it useful but I sure there are places for it.  I always use date() as in date("Y/m/d");.  See http://php.net/manual/en/function.date.php for date options.

[sungpeng]

date("w",$timestamp=time()); 

 

Is it with or without $timestamp make no different?

 

date("w");

[cypher86]

its simply the unix time and it's really useful when you have to deal with operations on dates.

[sungpeng]

$testing=date("w",$timestamp=time());
echo "$testing";

 

I see no different in output in this 2 codes. So can't understand why people need to use $timestamp in coding date.

 

$testing=date("w");
echo "$testing";

[Drummin]

Did you see the link I posted above?  What date format are you looking for?

The "w" gives you the numeric representation of the day of the week 0 (for Sunday) through 6 (for Saturday) when used with date();

[nethnet]

The time() function returns the current UNIX timestamp, which is the amount of seconds since the Unix Epoch (January 1st, 1970 0:00:00 GMT).

 

The date() function formats a date in the way specified.  As you have used, "w" will return the numerical representation of the day of the week.  By default, the date() function uses the current date and time for the return value, so using date("w") and date("w", time()) will return the exact same thing.  If, however, you wanted to know the day of the week exactly 100 days from now, you could use a combination of the two functions to do so:

 

<?php

$timestamp = time();

$onehundreddays = 60 * 60 * 24 * 100; // The amount of seconds in 100 days

$finaltime = $timestamp + $onehundreddays;

echo "In one hundred days, it will be " . date("l", $finaltime);

?>

 

As you can see, UNIX timestamps become very useful when you want to manipulate dates or calculate spans of time between two dates.  The second parameter of the date() function is entirely optional, and will default to the current timestamp, so putting the current value of time() in it is redundant and unnecessary.

 

I hope that helps your understanding of these two functions.

[sungpeng]

Thank nethnet