Xcode中的预期表达错误

Question

I am making a move function for a game and I get a expected expression error I can't figure out why, it seems legal what i did.

void Ant::move()
{
int dir=rand()%4;

if (dir==0)
{
    if ((y>0) && (world->getAt(x,y-1)==NULL))
    {
        world->setAt(x,y-1,world->getAt(x,y));
        world->setAt(x,y,NULL);
        y++;
    }
}
else
{
    if ((x<WORLDSIZE-1) && (world->getAt(x+1,y)==NULL))
    {
        world->setAt(x-1,y,world->getAt(x,y));
        world->setAt(x,y,NULL);
        x--;
    }
}
else
{
    if ((x<WORLDSIZE-1) && (world-getAt(x+1,y)==NULL))
    {
        world->setAt(x+1,y,world->getAt(x,y));
        world->setAt(x,y,NULL);
        x++;
    }
}
}

The problem is the second else call.

Answer 1

I think the problem is:

world-getAt(x+1,y)==NULL

You forgot the >

world->getAt(x+1,y)==NULL

In the second if statement.

Answer 2

There is an if missing after the first else. You have now

if {
    ...
} else { // here you need an if - or revise the structure

} else {

}

For instance try ...

void Ant::move()
{
    int dir=rand()%4;

    if (dir==0)
    {
        if ((y>0) && (world->getAt(x,y-1)==NULL))
        {
            world->setAt(x,y-1,world->getAt(x,y));
            world->setAt(x,y,NULL);
            y++;
        } else
        if ((x<WORLDSIZE-1) && (world->getAt(x+1,y)==NULL))
        {
            world->setAt(x-1,y,world->getAt(x,y));
            world->setAt(x,y,NULL);
            x--;
        } else
        if ((x<WORLDSIZE-1) && (world-getAt(x+1,y)==NULL))
        {
            world->setAt(x+1,y,world->getAt(x,y));
            world->setAt(x,y,NULL);
            x++;
        }
    }
}