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  1. #include <stdio.h>
  2. #include <string.h>
  3.  
  4. typedef struct mynode{
  5. //some data
  6. struct mynode *left , *right;
  7. }mynode;
  8.  
  9. int main(int argc, char* argv[])
  10. {
  11. 	int i;
  12. 	int n = 5;
  13. 	int m = 10;
  14. 	mynode** p = (mynode**)malloc(n*sizeof(mynode*));					// Heap memory
  15.  
  16. 	// Or memset(p, (int)NULL, n * sizeof(mynode*));
  17. 	for(i = 0; i < n; ++i)
  18. 	{
  19. 		p[i] = NULL;
  20. 	}	
  21.  
  22. 	for(i = 0; i < n; ++i)
  23. 	{
  24. 		p[i] = (mynode*)malloc(m*sizeof(mynode));						// Heap memory
  25. 		memset(p[i], (int)NULL, m * sizeof(mynode));// Method 2, include <cstring> or <string.h>
  26. 		printf("left=%p, right=%p\n", p[i][0].left, p[i][0].right);
  27. 		// p[i] = &n;								// This case don't use delete [] p[i]. (Pointer to a variable)
  28. 	}
  29.  
  30. 	/*** do something ***/
  31.  
  32. 	for(i = 0; i < n; ++i)
  33. 	{
  34. 		free(p[i]);
  35. 	}
  36. 	free(p);
  37.  
  38. 	return 0;
  39. }
Success #stdin #stdout 0s 2184KB
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Standard input is empty
stdout
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left=(nil), right=(nil)
left=(nil), right=(nil)
left=(nil), right=(nil)
left=(nil), right=(nil)
left=(nil), right=(nil)
https://ideone.com/gtkVHT
language:
C (gcc 8.3)
created:
9 years ago
visibility:
public

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