Talk:For

Overstuffing the for

The complete syntax of the loop for is:

for( initializer, initializer, ...; condition; increment, increment, ... ) loop

We can use as many initializers and increments as we want, separated by commas.

For example, to initialize the start and end values, which even looks interesting to use:

    list num; integer totNum; integer i;

    // totNum = llGetListLength(num);
    //
    // for ( i = 0, totNum = llGetListLength(num); i < totNum; i++)
    // {
    //
    // }

    for ( i = 0, totNum = llGetListLength(num); i < totNum; i++)
    {

    }

Other examples look more weird than useful, but they work:

• Adding the elements of a list of numbers:

    list num = [ 2, 3, 5, 8, 13, 21, 34, 55, 89, 144 ];
    integer sum; integer totNum; integer i;

    for ( i = 0, totNum = llGetListLength(num), sum = 0; i < totNum; sum += llList2Integer(num, i), i++);  // no loop body

    llOwnerSay("sum = " + (string)sum);

• Counting dice rolls until getting a double six:

    integer dice1; integer dice2; integer roll;

    for ( roll = 0, dice1 = 0, dice2 = 0; dice1 < 6 || dice2 < 6; roll++, dice1 = (integer)llFrand(6) + 1, dice2 = (integer)llFrand(6) + 1 );  // no loop body

    llOwnerSay("Double six after " + (string)roll + " rolls");

• Packing two fors in one:

    integer i; integer j;

    // for ( i = 0; i < 5; i++ )
    // {
    //     for ( j= 0; j < 3; j++ )
    //     {
    //         llOwnerSay("i=" + (string)i + " j=" + (string)j);
    //     }
    // }

    for ( i = 0, j = 0; i < 5; j++, i += (j == 3), j *= (j != 3) )
    {
        llOwnerSay("i=" + (string)i + " j=" + (string)j);
    }

• Three in one:

    integer i; integer j; integer k;

    // for ( i = 0; i < 5; i++ )
    // {
    //     for ( j= 0; j < 3; j++ )
    //     {
    //         for ( k = 0; k < 4; k++ )
    //         {
    //             llOwnerSay("i=" + (string)i + " j=" + (string)j + " k=" + (string)k);
    //         }
    //     }
    // }

    for ( i = 0, j = 0, k =0; i < 5; k++, j += (k == 4), k *= (k != 4), i += (j == 3), j *= (j != 3) )
    {
        llOwnerSay("i=" + (string)i + " j=" + (string)j + " k=" + (string)k);
    }

SuzannaLinn Resident (talk) 07:09, 24 October 2024 (PDT)