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Thread: Research about Randomising , need assistance here.

  1. #1
    Join Date
    Jan 2013
    Posts
    5

    Research about Randomising , need assistance here.

    I am currently, research the randomizing,
    and i try to make a minesweeper game to play around with my new function.
    My plan is lay ten mines inside the mine table
    but after i run my code , i got some unexpected problem which is i can't have
    ten random mines everytime i refresh it.
    I have fix some loop and code but the problem is still here.

    My current lay mines code looks like this :

    <script type="text/javascript">
    function addmines (x) {
    var n = 10; //number of mines
    var mines = []; //an empty array
    while (n>0) {
    var row = Math.floor(1+Math.random()*10);
    var col = Math.floor(1+Math.random()*10);

    if (row >= 0 && row < 10){
    if (col >= 0 && col < 10) {
    var id = "r"+ row + "c" + col;

    n++;

    var a = document.createElement("img");
    a.src = "mine32.gif";
    a.height = 30;
    a.width = 30;
    document.getElementById(id).appendChild(a);


    }
    }

    }
    return x;
    }

    </script>



    And this is my tables

    //Creates Table
    document.write('<table>');
    //for loop that creates the row, increments from 0 to 9 each time it reiterates
    for (var row=0; row<9; row++) {
    //creates the table row
    document.write('<tr>');
    //a nested for loop that reiterates 9 times creating the <td>'s and then exits to the parent for loop.
    for (var col=0; col<9; col++) {
    //references all the <td>'s with a specific id attribute.
    document.write('<td id="r', row, 'c', col, '">');
    //document.write('&nbsp;');
    //closes the <td>
    document.write('</td>');
    }
    //closes the <tr> or row in plain English
    document.write('</tr>');
    }
    //closes the <table> tag
    document.write('</table>');

    addmines();


    Can someone give me suggestion and assistance that allow me to correct my mistakes please?

  2. #2
    Join Date
    Aug 2008
    Location
    Sweden
    Posts
    227
    There are several issues. First of all, there's an error: you're trying to add an image to a <td> element that doesn't exist. So either too few <td>s are created or the numbers for your random row and column are too high or low. (Always check the console!)

    Secondly you're saying n++ instead of n-- which means that the while loop will loop forever. (n>0 will always be true.)

    Some unnecessary things that can be removed are the empty mines array and these checks:
    Code:
    if (row >= 0 && row < 10){
    if (col >= 0 && col < 10) {
    because you already know row and col will be within those boundaries when you set them. The argument variable x is also unused and can be removed.

    Here's the fixed code:
    Code:
    function addmines () {
        var n = 10; //number of mines
        while (n>0) {
            var row = Math.floor(Math.random()*9);
            var col = Math.floor(Math.random()*9);
    
            var id = "r" + row + "c" + col;
    
            var td = document.getElementById(id);
            if (td.children.length > 0)
                continue; //there's already a mine here
    
            n--;
    
            var a = document.createElement("img");
            a.src = "mine32.gif";
            a.height = 30;
            a.width = 30;
            td.appendChild(a);
    
        }
    }
    Code:
    //Creates Tabledocument.write('<table>');
    //for loop that creates the row, increments
    //from 0 to 9 each time it reiterates
    for (var row=0; row<9; row++) {
        document.write('<tr>');
        //a nested for loop that reiterates 9 times creating
        //the <td>'s and then exits to the parent for loop.
        for (var col=0; col<9; col++) {
            document.write('<td id="r', row, 'c', col, '">');
            document.write('</td>');
        }
        document.write('</tr>');
    }
    document.write('</table>');
    
    addmines();
    Last edited by ReFreezed; 01-03-2013 at 03:06 PM.

  3. #3
    Join Date
    Jan 2013
    Posts
    5
    Thank you for reply ,
    i have fixed it ,
    i had a stupid mistake ,
    everything is good now , thank you very much
    Last edited by anson920520; 01-03-2013 at 03:18 PM.

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