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  1. #include <stdlib.h>
  2. #include <stdio.h>
  3.  
  4. typedef struct Cheapmap Cheapmap;
  5.  
  6. struct Cheapmap {
  7.     unsigned count;
  8.     void *table[256];
  9. };
  10.  
  11. void insert(Cheapmap *chm, void *p)
  12. {
  13.     unsigned char *u = p;
  14.  
  15.     if (chm->table[*u] == NULL) {
  16.         chm->table[*u] = p;
  17.         chm->count++;
  18.     }
  19. }
  20.  
  21. void **keys(Cheapmap *chm)
  22. {
  23.     void **k = calloc(chm->count + 1, sizeof(*k));
  24.     void **p = k;
  25.  
  26.     unsigned i;
  27.  
  28.     for (i = 0; i < 256; i++) {
  29.         if (chm->table[i]) *p++ = chm->table[i];
  30.     }
  31.  
  32.     return k;
  33. }
  34.  
  35.  
  36. int main()
  37. {
  38.     Cheapmap chm = {0};
  39.  
  40.     insert(&chm, "banana");
  41.     insert(&chm, "strawberry");
  42.     insert(&chm, "apple");
  43.     insert(&chm, "papaya");
  44.  
  45.     void **k = keys(&chm);
  46.     unsigned i = 0;
  47.  
  48.     while (k[i]) {
  49.         puts(k[i]);
  50.         i++;
  51.     }
  52.  
  53.     free(k);
  54.  
  55.     return 0;
  56. }
  57.  
Success #stdin #stdout 0s 4444KB
comments (?)
stdin 
Standard input is empty
stdout 
apple
banana
papaya
strawberry
https://ideone.com/jo4ocg
language:
C (gcc 8.3)
created:
5 years ago
visibility:
public

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