Using array.sort

[Derek Parnell]

On Wed, 24 Jan 2007 22:55:57 -0500, Heinz wrote:

 
> Hi Chris, i still don't get it hahaha. Replace the int in your
> example by a char[] str; How the hell opCmp can compare a string,
> what value of type int should return? thx

This is a good question. It all depends on how you want to define when one
string is less than another. 

Here is one definition, just for example purposes.

import std.stdio;

 class myclass {
    char[] cs;
    this(char[] d) { cs = d.dup; }

    int opCmp (Object obj)
    {
       // Strings contain unicode code-points.
       // Shorter strings compare "less than" longer strings.
       // Equal length strings compare respective unicode code-points.

       if (cs.length < (cast(myclass)obj).cs.length)
           return -1;
       if (cs.length > (cast(myclass)obj).cs.length)
           return  1;
       if (cs == (cast(myclass)obj).cs)
           return 0;

       // Ok, so they are different. Now we look at each code-point.
       dchar[] temp_self  = std.utf.toUTF32(cs);
       dchar[] temp_other = std.utf.toUTF32((cast(myclass)obj).cs);

       foreach(int i, dchar c; temp_self)
       {
          dchar oc;
          oc = temp_other[i];
          if (c < oc)
             return -1;
          if (c > oc)
             return  1;
       }
       throw new Error("Failed to find difference. Should never happen.");
    }
 }

void show(myclass[] Data, char[] Title)
{
   writefln("\n\n%s\n--------------", Title);
   foreach(myclass x; Data)
   {
        writefln("%s", x.cs);
   }
}

void main()
{
   myclass[] A;
   A ~= new myclass("one");
   A ~= new myclass("two");
   A ~= new myclass("three");
   A ~= new myclass("four");
   A ~= new myclass("five");
   A ~= new myclass("six");
   A ~= new myclass("seven");
   A ~= new myclass("eight");
   A ~= new myclass("nine");
   A ~= new myclass("ten");

   show(A, "Before");
   A.sort;
   show(A, "After");

}

 =============

C:\temp>dmd -run test.d


Before
--------------
one
two
three
four
five
six
seven
eight
nine
ten


After
--------------
one
six
ten
two
five
four
nine
eight
seven
three

-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
"Down with mediocrity!"
25/01/2007 4:03:16 PM