C program

EMPS intranet

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Value and type of last evaluated expression: Address of array element: Address of array elementx: (none)

The pointer el inside calculate_area() points to ellie inside main() so el->member refers to ellie.member.

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Code

 Header...
#define PI 3.14159265358979

typedef struct ellipse {
  float centre[2];
  float axes[2];
  float orientation;
  float area;
}Ellipse;

 void calculate_area(Ellipse *el){
»  el->area=PI*el->axes[0]*el->axes[1];
}
 ... 


 int main(){
»  Ellipse ellie;

»  printf("Centre? (x,y)\n");
»  scanf("%f %f", &ellie.centre[0], &ellie.centre[1]);
 
  // NB: in a real program we should check
  // the axes are actually > 0 
»  printf("Length of axes ( > 0 )?\n");
»  scanf("%f %f", &ellie.axes[0], &ellie.axes[1]);

»  printf("Orientation to the vertical?\n");
»  scanf("%f", &ellie.orientation);

»  calculate_area(&ellie);

»  return 0;
}
 ...

Memory

calculate_area()
128	129	130	131
el = 148

main()
				148	149	150	151
				ellie.centre[0] = -2.68816e+17
152	153	154	155	156	157	158	159
ellie.centre[1] = -4.49525e+33				ellie.axes[0] = 5.05323e-20
160	161	162	163	164	165	166	167
ellie.axes[1] = 9.04191e-12				ellie.orientation = 1.96563216e+24
168	169	170	171
ellie.area = -2.64774408e-25

NB: the actual memory address of each variable is the
address shown plus 4289576160 (0xFFADBCE0).

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Input was:

7.2 4.5 1.2  4.3 1.7

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Output

Centre? (x,y)
Length of axes ( > 0 )?
Orientation to the vertical?

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