PHP date（）可靠性

Question

I am building a package that heavily relies on the current week number of the year as well as the forthcoming 4 or 5 week numbers. I know that sounds kind of confusing but lets say this week amounts to the 51st one of the year. The next 4 week numbers would be:

1. 52
2. 1
3. 2
4. 3

My Question:

How reliable is PHP's date() function? The library isn't very well documented and the comments underneath make me a little nervous about using it. I am using the following to get the current week number:

echo $weekNumber = date("W");

Is that a reliable way of working with dates? Any recommendations? I am not very good with dates and times and the sheer size of the various functions available in PHP's native library has left me very confused (time(), strtotime(), date() etc).

Answer 1

I've just done a quick test with the following code:

echo date('W', strtotime('2011/12/31')) . '<br>';
echo date('W', strtotime('2011/12/31 +1 week')) . '<br>';
echo date('W', strtotime('2011/12/31 +2 week')) . '<br>';
echo date('W', strtotime('2011/12/31 +3 week')) . '<br>';

Here we start with the 31st Dec 2011 (last day this year), then we print 3 more W weeks, which gives this output:

52
01
02
03
04

Which does exactly what you want. If PHP's date() function didn't work properly, it would have either been removed (bad!), or rewritten until it did work.