PHP supports a variety of ways to sort an array when
I say
sort, I am referring to an alphabetical sort if it is a string,
and a numerical
sort if it is a number. When sorting an array,
you must keep in mind that an
array consists of several pairs
of keys and values. Thus, an array can be sorted
based upon
the values or the keys. Also, you can sort the values and keep
the
corresponding keys matched up or sort the values and
have them receive new
keys.
To sort the values, without regard to the keys,
you use
sort().
To sort these values again without regard to the keys,
in
reverse order, you use rsort().
The syntax for every sorting function
is like this:
function($Array); So, sort() and rsort() are simply: sort($Array); rsort($Array);
To sort the values, while maintaining the correlation
between
the value and its key, you use asort().
To sort them in reverse, while
maintaining the key
correlation, you use arsort().
To sort by the keys, while still maintaining the correlation
between the key and its value, you use ksort().
Conversely,
krsort() will sort the keys in reverse.
Last, shuffle() randomly reorganizes the order of an
array.
As an example of sorting arrays, you'll create a list of
students
and the grades they received on a test, then sort this list first
by
grade then by name.
Create the array:
$Grades = array( "Richard"=>"95", "Sherwood"=>"82", "Toni"=>"98", "Franz"=>"87", "Melissa"=>"75", "Roddy"=>"85" );
Print a caption and then print each element of
the array using
a loop.
print ("Originally, the array looks
like this:<BR>");
for ($n = 0; $n < count($Grades);
$n++) {
$Line = each ($Grades);
print ("$Line[key]'s grade is
$Line[value].<BR>\n");
}
Sort the array in reverse order by values to determine
who had
the highest grade.
arsort($Grades);
Because you are determining who has the highest
grade, you need
to use arsort() instead of asort().
The latter, which sorts
the array by numeric order, would
order them 75, 82,
85, etc. and not the desired 98, 95, 87,
etc.
