Array of Struct issue

Hello, I am new to C and I have to work with it because of need to use existing code. I went through several sites and this is my last hope. Please advise.


I have a file that defines a simple struct .. something like:

Code:

---

typedef struct{
  double x;
  double y;
  double z;
} Point;

---

Now, I have an array of type point

Point setA[anchorSize];

what I am trying to do but having issues with is as follows:

Code:

---

for(i=0;i<foobar;i++){
  setA[i]={pt1,pt2,pt3};//pt1-pt3 are some double values
}

---

However, that does not work for me. I am not sure what I am doing wrong or if this is even allowed but I get something like this for error:
remodelProtein.c:261: parse error before '{' token

This however does compile but it seems silly:

Code:

---

for{blabla}{
  Point tempPt={pt1,pt2,pt3};
  SetA[i]=tempPt;
}

---

Do I have to do it this way? Please advise

Much Much Much love and thanks for any help you can provide :smile:

Check a few lines above the error line. It looks like you forgot a semi-colon at the end of some line and the compiler got confused.

what about

Code:

---

for(i=0;i<foobar;i++){
  setA[i].x=pt1;
  setA[i].y=pt2;
  setA[i].z=pt3;
}

---

or

Code:

---

Point tempPt={pt1,pt2,pt3};
for{blabla}{
  SetA[i]=tempPt;
}

---

Kurt

Well,

Code:

---

for{}

---

shouldn't even compile.

I think the first variant is the best. I've more readable. Could you point out which line is the one that's actually giving you problems, and some context?

I do not believe you can do the following:

Code:

---

for(i=0;i<foobar;i++){
  setA[i]={pt1,pt2,pt3};//pt1-pt3 are some double values
}

---

...because that method is only possible for initialization. Since setA[] has already been initialized earlier, you will need to set each field individually, as ZuK wrote.

Hope this helps...

I thought that was clear.
the statement

Code:

---

setA[i]={pt1,pt2,pt3};

---

is not valid c.
This syntax can only be used to initialize variables.
The above statement is not an initialization. Is an assignement -> syntax error.
Kurt
Edit: KidA was a lot faster. :)

>is not valid c.

I'm never sure wether that can actually be used and I always get confused, because it's not a problem in initiaisers, I sort of expect the compiler to use a temporary variable and then assign it, though that may be C++ (I did C++ before C so some things I'm still confused about).

But yes, you're right.

sorry, ok this is a snipped of the code that WORKS

Code:

---

                       
                        currAtom=rnaList[RNA_FILE_COUNTER-1].atomList[p];
                        if(q<anchorSize*3){
                                Point temp1={currAtom.x[anchorPos[0]],currAtom.y[anchorPos[0]],currAtom.z[anchorPos[0]]};
                                Point temp2={currAtom.x[anchorPos[1]],currAtom.y[anchorPos[1]],currAtom.z[anchorPos[1]]};
                                Point temp3={currAtom.x[anchorPos[2]],currAtom.y[anchorPos[2]],currAtom.z[anchorPos[2]]};
                                SetA[q+0]=temp1;
                                SetA[q+1]=temp2;
                                SetA[q+2]=temp3;
                                q=q+3;
                        }

---

and when this snippet of the code is replaced with the following one I am getting way too many errors:

Code:

---

currAtom=rnaList[RNA_FILE_COUNTER-1].atomList[p];
                        if(q<anchorSize*3){
                                SetA[q+0]={currAtom.x[anchorPos[0]],currAtom.y[anchorPos[0]],currAtom.z[anchorPos[0]]};
                                SetA[q+1]={currAtom.x[anchorPos[1]],currAtom.y[anchorPos[1]],currAtom.z[anchorPos[1]]};
                                SetA[q+2]={currAtom.x[anchorPos[2]],currAtom.y[anchorPos[2]],currAtom.z[anchorPos[2]]};
                                q=q+3;
                        }

---

Sec i will try to get a better error report.

aha zuk and kidA, just saw your post. Ok I guess that kindav sux for me as it will add more lines as I have a lot of this babies. I cant quite make a nice for loop around it as that would interfere with my pattern loops.

I was hoping some fancy pointer wonders to help me out but I can live with it (:

thanks guys!!!

Anonymous temporary structures are not a feature of standard C (at least pre-C99), so the assignment doesn't work. Some compilers support anonymous temporary structures, but I'd not depend on it.

I'd recommend coding the thing as something like:

Code:

---

typedef struct{
  double x;
  double y;
  double z;
} Point;

void setPoint(Point *p, double x, double y, double z)
{
  p->x = x;
  p->y = y;
  p->z = z;
}

---

and in your loop, do something like:

Code:

---

for(i=0;i<foobar;i++)
{
  setPoint(&setA[i], pt1, pt2, pt3);
}

---

Assuming that your compiler can return structures, you could also write a helper fuction:

Code:

---

Point point(double x, double y, double z)
{
  Point p = {x, y, z};  // initialization, not assignment
  return p;
}

---

and in your loop do

Code:

---

  setA[i] = point(pt1, pt2, pt3);

---

This requires structure return, which IIRC is a required feature in C90.

I hope this helps.