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  1. #include <stdlib.h>
  2. #include <stdio.h>
  3.  
  4. int main()
  5. {
  6.   /* The compiler allocates space for "Hello" and '\0' (5 + 1 chars)
  7.    * and stores the address in aString1.
  8.    */
  9.   const char *aString1 = "Hello";
  10.   /* The compiler allocates 10 chars and initializes
  11.    * it with "World" (and the '\0' for terminator).
  12.    */
  13.   const char aString2[10] = "World";
  14.   /* The compiler determines length of initializer "I'm here."
  15.    * (9 + 1) and allocates the array of appropriate size.
  16.    */
  17.   const char aString3[] = "I'm here.";
  18.   /* allocate storage for array (3 const char*) */
  19. #if 0 /* the usual way */
  20.   const char **array = malloc(3 * sizeof (const char*));
  21. #else /* how Matheus wants to do it */
  22.   const char **array = NULL;
  23.   array = realloc(array, 3 * sizeof (const char*));
  24. #endif /* 0 */
  25.   /* assign contents (using it like an array) */
  26.   array[0] = aString1;
  27.   array[1] = aString2;
  28.   array[2] = aString3;
  29.   /* apply array to another variable array2 */
  30.   const char **array2 = array; /* assigns the address only */
  31.   /* use it: */
  32.   printf("array2[0]: '%s', array2[1]: '%s', array2[2]: '%s'\n",
  33.     array2[0], array2[1], array2[2]);
  34.   /* throw away storage of array (and array2) */
  35.   free(array);
  36.   /* Attention! array, array2 become wild pointers at this point
  37.    * and may not be accessed (except new, valid addresses are assigned).
  38.    * However, aString1, aString2, aString3 are still intact.
  39.    */
  40.   printf("aString1: '%s', aString2: '%s', aString3: '%s'\n",
  41.     aString1, aString2, aString3);
  42.   /* done */
  43.   return 0;
  44. }
  45.  
Success #stdin #stdout 0s 9424KB
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stdin
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Standard input is empty
stdout
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array2[0]: 'Hello', array2[1]: 'World', array2[2]: 'I'm here.'
aString1: 'Hello', aString2: 'World', aString3: 'I'm here.'
https://ideone.com/4JYGH7
language:
C (gcc 8.3)
created:
8 years ago
visibility:
public

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