Struct question

**Death_Wraith** · 06-01-2004

when the last member (down) is acsessed, it crashes.

Code:

struct key{bool left;
           bool right;
           bool up;
           bool down;};

Is there somthing wrong with how i declared this? All the other members work fine.

DW

**DavidP** · 06-01-2004

If something is going wrong during runtime, then no, everything is okay with that declaration. It is something wrong with how you are using it in your code. Post your code.

If you are getting an error when you compile, post the error.

**skorman00** · 06-01-2004

It may be crashing because it was never initialized. Some compilers will do that, where others will just tell what happens to be in that memory block at that time.

**major_small** · 06-01-2004

Originally Posted by skorman00

It may be crashing because it was never initialized. Some compilers will do that, where others will just tell what happens to be in that memory block at that time.

no, if the program's crashing, it has little to nothing to do with the comper...

I think what you mean is that some compilers will give you an error and halt compilation, where others will just compile the program with maybe a warning, and the program will give you the contents of that memory address...

edit: this thread should never have been started: http://cboard.cprogramming.com/showthread.php?t=53495

**Death_Wraith** · 06-01-2004

>> edit: this thread should never have been started: http://cboard.cprogramming.com/showthread.php?t=53495

yup yup i know. i acidently clicked new thread, instead of post reply

silly me. Sorry about that!

Regardless, thats where the code is, and can anyone see anything wrong with it? it crashes during

Code:

void User_Laser::Collision(Enemy *Baddy[4][8], User_Laser *laser)
{
  int i,k;



  for(i=1;i<5;i++)
  {
        for(k=1;k<9;k++)
        {
              if(laser->y1 <= Baddy[i][k]->Baddy_Collision.left)
              {
                    if(laser->Bullet.top >= Baddy[i][k]->Baddy_Collision.top &&  laser->Bullet.top <= Baddy[i][k]->Baddy_Collision.right && Baddy[i][k]->Dead == false)
                    {
                         Baddy[i][k]->Dead = true;
                         laser->Obsolete = true;
                    }
              }
        }
  }
}

cheers, and sry again about the double post ;D

DW

**Hunter2** · 06-01-2004

I don't see where any key object is created or accessed...

**thefroggy** · 06-01-2004

Check your for loops. You're overstepping your array bounds.

Code:

for(i=1;i<5;i++)

should be

Code:

for(i=0;i<4;i++)

and

Code:

for(i=1;i<9;i++)

should be

Code:

for(i=0;i<8;i++)

Remember that arrays are indexed starting with 0 -- so an array with 4 elements would have indices 0-3. (not 1-4)

-tf

**bennyandthejets** · 06-01-2004

Looks like that's your answer deathwraith. Keep it in the same thread next time though.

**Death_Wraith** · 06-01-2004

>>Keep it in the same thread next time though.

Will do!

Again, my bad.

I changed the bounds of all my arrays( <5 to <4, <9 to <8, etc), and low and behold, it work! (imagine that!)

But when i changed the bounds down by one, only a 3 by 7 array of baddies appeared, as opposed to a 4 x 8. how do i fix this?

This is my current newing...

Code:

  for(int k=1;k<5;k++)
  {
        for(int z = 1;z<9;z++)
        {
                Baddy[k][z] = new Enemy(z,k);
        }
  }

this is what I tried, but didn't solve the problem...

Code:

  for(int k=1;k<6;k++)
  {
        for(int z = 1;z<10;z++)
        {
                Baddy[k][z] = new Enemy(z,k);
        }
  }

how do i change this so i get my desired 4 x 8 array again? thanks for the help!

cheers

DW

**bennyandthejets** · 06-01-2004

'k' and 'z' should start at zero thinks I:

Code:

 for(int k=0;k<5;k++)
  {
        for(int z = 0;z<9;z++)
        {
                Baddy[k][z] = new Enemy(z,k);
        }
  }

I thought that's what you had changed.

**Death_Wraith** · 06-02-2004

When I do that, should i keep the other counters from <5 && < 9 and starting at 1 or 0?

DW

**elad** · 06-02-2004

depends on how they are used. If the counters are used to keep track of how many times the body of the loop is done, then both ranges are equivalent and no biggy either way. However, if the counter is used as an array index, then you can get into trouble if the counter is out of range for the array.

**Hunter2** · 06-02-2004

Example of looping through an array:

Code:

MyStruct array[20];    //There are 20 elements in the array

for(int i = 0; i < 20; ++i)    //The loop looks like this.
{
    //do something with array[i].
}

Note that i starts at 0, and the loop condition is "i < (size of the array)". Also note that this loop condition only lets the loop keep going until i reaches 19; 20 never gets run. So altogether 20 elements are checked, starting at 0 and ending at 19.

**Crawdawg** · 06-02-2004

A general rule to keep in mind is that all true number systems start from zero. You will save yourself many headaches by following this rule.

**Death_Wraith** · 06-02-2004

Yup, well that worked well. I'm just learning c++ coming from VB, so I forget every once and a while (read normaly

) that they start at 0! Cheers, and thx for the help!

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