ex-21-5

这是一个wmlscript的源代码程序

/*
 * WMLScript for battleships game.
 */

/*
 * Initialize the grid. For simplicity, we don't place the ships randomly.
 * Instead, there is one fixed grid layout.
 */
extern function init (  )
{
    /* Initialize all the display variables to a space. */
    for (var i=0; i<4; ++i) {
        for (var j=0; j<4; ++j) {
            WMLBrowser.setVar ("d_" + i + "_" + j, ' ');
        }
    }

    /* Initialize the secret locations of the ships. The layout looks like:
     *     * * * D
     *     D D * D
     *     * * * *
     *     B B B B
     */
    WMLBrowser.setVar ("ships", "***DDD*D****BBBB");
    WMLBrowser.setVar ("remain", 8);
    WMLBrowser.refresh ();
}

/*
 * Handle a guess at a square.
 */
extern function guess (gr, gc)
{
    /* Read the positions of the ships. */
    var ships = WMLBrowser.getVar ("ships");

    /* Read the number remaining as an integer. */
    var remain = Lang.parseInt (WMLBrowser.getVar ("remain"));

    /* Ignore this guess if user has already won. */
    if (remain == 0)
        return;

    /* Calculate the name of the cell's display variable. */
    var cellname = "d_" + gr + "_" + gc;

    /* Ignore this guess if already guessed or not on board.
     * Unguessed cells contain a space character.
     */
    if (WMLBrowser.getVar (cellname) != ' ')
        return;

    /* Find what's in the cell. */
    var hit = String.charAt (ships, 4*gr + gc);

    /* Reduce remaining ships if appropriate. */
    if (hit != '*')
        --remain;

    /* Update variables accordingly and refresh display. */
    WMLBrowser.setVar ("remain", remain);
    WMLBrowser.setVar (cellname, hit);
    WMLBrowser.refresh (  );

    /* Congratulate the user if game is now over. */
    if (remain == 0)
        congrats (  );
}

/*
 * Print congratulatory message when game won.
 */
function congrats (  )
{
    /* Count number of shots required. */
    var shots = 0, hits = 0;
    for (var i=0; i<4; ++i) {
        for (var j=0; j<4; ++j) {
            var cell = WMLBrowser.getVar ("d_" + i + "_" + j);
            if (cell != ' ') {
                ++shots;
                if (cell != '*')
                    ++hits;
            }
        }
    }

    /* Calculate accuracy (proportion of shots on target). */
    var accuracy = hits / shots;

    /* Display message. */
    Dialogs.alert ("All ships sunk. "
                   + String.format ("You took %d shots. ", shots)
                   + String.format ("Accuracy: %.2f%%", accuracy * 100));
}