Quicksort

From Bennu Wiki
Jump to: navigation, search


Definition

INT quicksort ( <VOID POINTER array> , <INT elementsize> , <INT elements> , <INT dataoffset> , <BYTE datasize> , <BYTE datatype> )

Sorts an array by the Quicksort ordering algorithm.

This function is very handy for user defined types for elements in which a sort-variable is present. For simple arrays or arrays in which the first variable is the sort-variable, sort() can be used. For arrays in which the sort-variable is a String, ksort() can be used.

Parameters

VOID POINTER array - Pointer to the first element of the array to be sorted.
INT elementsize - The size of an element in the array in bytes.
INT elements - The number of elements in the array.
INT dataoffset - The number of bytes the sort-variable in each element is relative to the start of that element.
BYTE datasize - The size of the sort-variable in bytes.
BYTE datatype - The datatype of the sort-variable. (0:integer, 1:float)

Returns

INT: true

Example

Program sorting;

Type _player
    String name;
    int score;
End

Const
    maxplayers = 5;
Global
    _player player[maxplayers-1];
Begin

    // Insert some values
    player[0].name = "That one bad looking dude";
    player[1].name = "Ah pretty lame guy";
    player[2].name = "Some cool dude";
    player[3].name = "OMG ZOMG guy";
    player[4].name = "This person is ok";

    player[0].score = 70;
    player[1].score = 30;
    player[2].score = 80;
    player[3].score = 90;
    player[4].score = 50;


    // Show array
    say("-------------------- unsorted");
    for(x=0; x<maxplayers; x++)
        say(player[x].name + " - " + player[x].score);
    end

/* Sort by name ( quicksort() can't be used to sort Strings,
   as a String in Fenix is a pointer to the actual String,
   so it would sort the pointer addresses */

    // sort()
    sort(player); // sorts by name because name is the first variable in each element

    // Show array
    say("-------------------- name - sort()");
    for(x=0; x<maxplayers; x++)
        say(player[x].name + " - " + player[x].score);
    end

    // ksort()
    ksort(player,player[0].name,maxplayers);

    // Show array
    say("-------------------- name - ksort()");
    for(x=0; x<maxplayers; x++)
        say(player[x].name + " - " + player[x].score);
    end

/* Sort by score (sort() cannot be used here, because score is not the first variable) */

    // ksort()
    ksort(player,player[0].score,maxplayers);

    // Show array
    say("-------------------- score - ksort()");
    for(x=0; x<maxplayers; x++)
        say(player[x].name + " - " + player[x].score);
    end

    // quicksort()
    quicksort(&player[0],sizeof(_player),maxplayers,sizeof(String),sizeof(int),0);

    // Show array
    say("-------------------- score - quicksort()");
    for(x=0; x<maxplayers; x++)
        say(player[x].name + " - " + player[x].score);
    end

    // Wait until ESC is pressed
    Repeat
         frame;
    Until(key(_esc))

End

Used in example: say(), sort(), ksort(), quicksort(), type, array, pointer