C program

EMPS intranet

Hi! Hi! Start program

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

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Code

 Header...
// Flawed attempt at multiple memory allocations

#define M 3
 int main(){
»  int n;
»  float *p;

»  printf("Size of each vector?\n");
»  scanf("%d", &n);// Find the row size

»  for ( int i=0;i<M; ++i) 
    p=xmalloc(n*sizeof *p);// Allocate rows

  // Do something useful...

»  return 0;
}
 ...

Memory

Allocated memory

128	129	130	131	132	133	134	135
128[0] = 0				128[1] = 0


144	145	146	147	148	149	150	151
144[0] = 0				144[1] = 0


160	161	162	163	164	165	166	167
160[0] = 0				160[1] = 0

main()
296	297	298	299	300	301	302	303
n = 761222277				p = -2551974503

main(): for()
304	305	306	307
i = 0

NB: the actual memory address of each variable is the
address shown plus 4293785848 (0xFFEDF8F8).

The actual address of allocated memory is the
address shown plus 148902144 (0x8E01100).

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Input was:

2 4

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

Output

Size of each vector?

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Try stepping through the code

Code

Allocated memory

main()

main(): for()

Output