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Hi!   Hi!           Start main()

Try stepping through the code


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

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Code

 Header...
#define NDIM 2 typedef struct particle { float x[NDIM]; float mass; struct particle *next; }Particle; // Allocate a new particle and add it to the END of the list
struct particle* newparticle(Particle *first){
  ...
» Particle *p, *last=first; » p=xmalloc(sizeof *p); » printf("Please enter the mass and x and y values.\n"); » scanf("%f %f %f", &p->mass, &p->x[0], &p->x[1]); » p->next=NULL; » if (first==NULL) return p;// New list // Find the last element » while (last->next!=NULL) last=last->next; » last->next=p; » return first;
} int main(){
  ...
» int i, n; » Particle *first=NULL; » printf("How many structures would you like?\n"); » scanf("%d", &n); » for (i=0; i<n; ++i) first=newparticle(first); » for ( Particle *p=first;p!=NULL; p=p->next) printf("Mass: %f position: (%g, %g)\n", p->mass, p->x[0], p->x[1]); » return 0;
}
Memory

Allocated memory

128
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128.x[0] = 4.74774e+17
128.x[1] = 2.02286e-11
136
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128.mass = 1.68604484e+15
128.next = -155423654

152
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152.x[0] = 7.18408e-08
152.x[1] = -nan
160
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152.mass = 15.8481331
152.next = -162042042

176
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176.x[0] = -7.88792e-08
176.x[1] = -2.49264e+21
184
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176.mass = -0.262313485
176.next = -158896846

200
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200.x[0] = -4.37399e-33
200.x[1] = 1.59082e+11
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200.mass = -8.79210362e-38
200.next = -157372747

newparticle()

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first = -4125290664
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359
?
?
?
?
p = -4291912541
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last = -4125290664

newparticle()

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first = NULL
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?
?
?
?
p = -4291912541
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last = NULL

newparticle()

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first = -4125290664
352
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?
?
?
?
p = -4291912541
360
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last = -4125290664

newparticle()

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first = -4125290664
352
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359
?
?
?
?
p = -4291912541
360
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363
last = -4125290664

main()

460
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i = 200
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n = -144657593
first = NULL

main(): for()

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p = -4125290664

NB: the actual memory address of each variable is the
address shown plus 4291912592 (0xFFD16390).

The actual address of allocated memory is the
address shown plus 166621800 (0x9EE7268).

Show Advanced options

.

Input was:

4 
4.1 2.4 7.7 
5.0 6.3 8.6 
3.6 4.3 2.91 
7.2 5.7 6.1

Show output (Before looking at the output, work out what you think it put should be and see if you are right.)

Output

How many structures would you like?
Please enter the mass and x and y values.
Please enter the mass and x and y values.
Please enter the mass and x and y values.
Please enter the mass and x and y values.
Mass: 4.100000 position: (2.4, 7.7)
Mass: 5.000000 position: (6.3, 8.6)
Mass: 3.600000 position: (4.3, 2.91)
Mass: 7.200000 position: (5.7, 6.1)
                                                                                                                                                                                                                                                                       

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