Thread: for loop gone mad

my understanding of for loops is it sets the variable to 10 say then counts up/down to the next instruction. for example

Code:

for (x = 10; x > 0; x--)
{
     printf("%d ", x);
}

will print out 10 9 8 7 6 5 4 3 2 1 where as if i set x >= 0 in the above loop it would print a zero as well.

why then does the last for loop in the below code count down to 0 when x is >= 0 but if tell it to run till x > 0 its an infinite loop.

Code:

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int board[8][8], start_x_coordinate, start_y_coordinate, finish_x_coordinate, finish_y_coordinate, temp_x, temp_y;
    int route[20][20][1], route_count = 0, move = 1, found_branch = 0;
    int a, x, y;
    int player = 0, multiplyer_y = player ? -1 : 1;
    int count_loop = 0;

    start_x_coordinate = 2;
    start_y_coordinate = 0;
    finish_x_coordinate = 4;
    finish_y_coordinate = 6;
    temp_x = start_x_coordinate;
    temp_y = start_y_coordinate;
    // inistalize board
    for (y = 7; y >= 0; y--)
    {
        for (x = 0; x < 8; x++)
        {
            if ((y % 2 == 0 && x % 2 == 0) || (y % 2 != 0 && x % 2 != 0))
            {
                board[x][y] = 0; //good square
                printf("%d ", board[x][y]);
            }
            else
            {
                board[x][y] = 5; //invalid square
                printf("%d ", board[x][y]);
            }
        }
        printf("\n");
    }

    // work out routes
    a = 1;
    while (a)
    {
        count_loop++;
        //check the diagonal squares are still on the board
        if (((temp_x - 2 >= 0 && temp_x - 2 <= 7) && (temp_y + 2 * multiplyer_y >= 0 && temp_y + 2 * multiplyer_y <=7)) &&
            ((temp_x + 2 >= 0 && temp_x + 2 <= 7) && (temp_y + 2 * multiplyer_y >= 0 && temp_y + 2 * multiplyer_y <=7)))
        {
            //record branch
            route[route_count][move][0] = 2;
            move += 1;
            //jump left
            route[route_count][move][0] = 0;
            temp_x -= 2;
            temp_y += 2 * multiplyer_y;
            move += 1;
        }
        else if((temp_x - 2 >= 0 && temp_x - 2 <= 7) && (temp_y + 2 * multiplyer_y >= 0 && temp_y + 2 * multiplyer_y <=7))
        {
            // jump left from whites point of view
            route[route_count][move][0] = 0;
            temp_x -= 2;
            temp_y += 2 * multiplyer_y;
            move += 1;
        }
        else if ((temp_x + 2 >= 0 && temp_x - 2 <= 7) && (temp_y + 2 * multiplyer_y >= 0 && temp_y + 2 * multiplyer_y <=7))
        {
            //jump right
            route[route_count][move][0] = 1;
            temp_x += 2;
            temp_y += 2 * multiplyer_y;
            move += 1;
        }
        else
        {
            route[route_count][move][0] = -2;
            repeat:
            if (move >= 0)
            {
                for (x = move; x > 0; x--)
                {
                    printf("array at %d = %d\n", x, route[route_count][x][0]);
                    if (route[route_count][x][0] == 2)
                    {
                        //last branch in the route found
                        found_branch = x;
                        break;
                    }
                }
                if (found_branch != 0)
                {
                    temp_x = start_x_coordinate;
                    temp_y = start_y_coordinate;
                    move = 0;
                    for (x = 0; x <= found_branch; x++)
                    {
                        if (route[route_count][move][0] == 0)
                        {
                            temp_x -= 2;
                            temp_y += 2 * multiplyer_y;
                            move++;
                        }
                        else if (route[route_count][move][0] == 1)
                        {
                            temp_x += 2;
                            temp_y += 2 * multiplyer_y;
                            move++;
                        }
                        else
                        {
                            // just increment move to preserve branch record
                            move++;
                        }
                    }
                    // move is pointing at the move after the last branch so decrement move by 1 then jump right
                    route[route_count][move - 1][0] = 1;
                    temp_x += 2;
                    temp_y += 2 * multiplyer_y;
                    move += 1;
                }
                else
                {
                    printf("no more branches\n");
                    break;
                }
            }
            else
            {
                printf("move was less than 1\n");
                break;
            }
        }
        if (temp_x == finish_x_coordinate && temp_y == finish_y_coordinate)
        {
            printf("route found\n");
            //copy old route into new route
            for (x = move; x >= 0; x--) //<---- this one here
            {
                route[route_count + 1][x][0] = route[route_count][x][0];
            }
            found_branch = 0;
            route_count++;
            goto repeat;
        }
    }
    printf("took %d goes to find a route\n", count_loop);
    return 0;
}

coop