At 23:53 03.04.2003, Jonathan Pitcher said:
--------------------[snip]--------------------
>This email is long I apologize for that. It is my code and then what
>it returns and what I am wanting it to return. I don't think I
>understand how USORT works or even if I am using the right function for
>what I am looking for.
--------------------[snip]--------------------
The compare callback is expected to return anything < 0 if the first value
is less than the second (should sort _before_), 0 if they are identical,
and > 0 if the first value is greater than the second (should sort _after_).
Taking this, your comparison callback directs PHP this way:
if ($A["STARTDATE"] < $B["STARTDATE"]) { return 4; }
if $A starts before $B, $A is greater (after $B).
if both start dates are equal, or $B starts before $A, continue.
else if ($A["STARTTIME"] < $B["STARTTIME"]) { return 3; }
if $A starts before $B, $A is greater (after $B).
if both start times are equal, or $B starts before $A, continue.
else if ($A["ENDDATE"] > $B["ENDDATE"]) { return 2; }
if $A ends after $B, $A is greater (after $B).
if both end dates are equal, or $A ends before $B, continue.
else if ($A["ENDTIME"] > $B["ENDTIME"]) { return 1; }
if $A ends after $B, $A is greater (after $B).
if both end times are equal, or $A ends before $B, continue.
else if ($A["STARTDATE"] > $B["STARTDATE"]) { return -4; }
if $A starts after $B, $A is less (before $B).
if both start dates are equal, continue.
else if ($A["STARTIME"] > $B["STARTTIME"]) { return -3; }
if $A starts after $B, $A is less (before $B).
if both start times are equal, continue.
else if ($A["ENDDATE"] < $B["ENDDATE"]) { return -2; }
if $A ends before $B, $A is less (before $B).
if both end dates are equal, continue.
else if ($A["ENDTIME"] < $B["ENDTIME"]) { return -1; }
if $A ends before $B, $A is less (before $B).
if both end times are equal, continue.
else { return 0; }
they are identical.
I believe you see where the problem is. You may express your comparison in
a shorter and possibly clearer form like this (not tested but looks as if
it should work):
if ($A['STARTDATE'] < $B['STARTDATE']) return -1; // a starts before B
elseif ($A['STARTDATE'] == $B['STARTDATE']) { // starts at the
same day
if ($A['STARTTIME'] < $B['STARTTIME']) return -1; // a starts before B
elseif ($A['STARTTIME'] == $B['STARTTIME']) { // same start day
and time
// here both courses start at the same day/time,
// so we need to sort them by enddate/time
if ($A['ENDDATE'] < $B['ENDDATE']) return -1; // a ends before B
elseif ($A['ENDDATE'] == $B['ENDDATE']) { // ends at the
same day
if ($A['ENDTIME'] < $B['ENDTIME']) return -1; // a ends before B
elseif ($A['ENDTIME'] == $B['ENDTIME']) { // same end day
and time
// identical
return 0;
}
}
}
}
// we've tested all possibilities for A being less or equal to B
// so there's only one more choice left - A is greater :)
return 1;
--
>O Ernest E. Vogelsinger
(\) ICQ #13394035
^ http://www.vogelsinger.at/
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