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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3.  
  4. typedef struct _Animal Animal;
  5. struct _Animal {
  6.     const char *name;
  7.     void (*play)(Animal *);
  8. };
  9.  
  10. typedef struct _Dog Dog;
  11. struct _Dog {
  12.     Animal animal;
  13. };
  14.  
  15. void playDog(Animal *dog) {
  16.     printf("わんわん！%sだよ\n", ((Dog *)dog)->animal.name);
  17. }
  18.  
  19. Animal *newDog(const char *name) {
  20.     Dog *dog = (Dog *)malloc(sizeof(Dog));
  21.     dog->animal.name = name;
  22.     dog->animal.play = playDog;
  23.  
  24.     return (Animal *)dog;
  25. }
  26.  
  27. typedef struct _Cat Cat;
  28. struct _Cat {
  29.     Animal animal;
  30.     int sleep;
  31. };
  32.  
  33. void playCat(Animal *cat) {
  34.     printf("にゃあ！%sだよ\n", ((Cat *)cat)->animal.name);
  35.     if(((Cat *)cat)->sleep == 1) {
  36.         printf("...でも寝る\n");
  37.     }
  38. }
  39.  
  40. Animal *newCat(const char *name, int sleep) {
  41.     Cat *cat = (Cat *)malloc(sizeof(Cat));
  42.     cat->animal.name = name;
  43.     cat->animal.play = playCat;
  44.     cat->sleep       = sleep;
  45.  
  46.     return (Animal *)cat;
  47. }
  48.  
  49. int main(int argc, char *argv[])
  50. {
  51.     int i;
  52.     Animal *pets[] = {
  53.         newDog("ぽち"),
  54.         newCat("たま", 1)
  55.     };
  56.  
  57.     for(i = 0; i < (sizeof pets / sizeof pets[0]); i++) {
  58.         pets[i]->play(pets[i]);
  59.     }
  60.  
  61.     for(i = 0; i < (sizeof pets / sizeof pets[0]); i++) {
  62.         free(pets[i]);
  63.     }
  64.     return 0;
  65. }
  66.  
Success #stdin #stdout 0s 5288KB
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Standard input is empty
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わんわん！ぽちだよ
にゃあ！たまだよ
...でも寝る
https://ideone.com/7vMXUv
language:
C (gcc 8.3)
created:
11 days ago
visibility:
public

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