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bsearch

De cppreference.com
< c‎ | algorithm

Defined in header <stdlib.h>
void* bsearch( const void* key, const void* ptr, size_t count, size_t size,
               int (*comp)(const void*, const void*) );
Recherche un élément égal à l'élément pointé par key dans un tableau pointé par ptr. Le tableau contient des éléments count de size taille. Fonction pointée par comp est utilisé pour la comparaison d'objets .
Original:
Finds an element equal to element pointed to by key in an array pointed to by ptr. The array contains count elements of size size. Function pointed to by comp is used for object comparison.
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Sommaire

[modifier] Paramètres

key -
pointeur vers l'élément à rechercher
Original:
pointer to the element to search for
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ptr -
pointeur vers le tableau d'examiner
Original:
pointer to the array to examine
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count -
nombre d'éléments dans le tableau
Original:
number of element in the array
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size -
taille de chaque élément dans le tableau en octets
Original:
size of each element in the array in bytes
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comp - comparison function which returns ​a negative integer value if the first argument is less than the second,

a positive integer value if the first argument is greater than the second and zero if the arguments are equal. key is passed as the first argument, an element from the array as the second.
The signature of the comparison function should be equivalent to the following:

 int cmp(const void *a, const void *b);

The function must not modify the objects passed to it.

[modifier] Retourne la valeur

pointeur vers l'élément trouvé ou autrement NULL .
Original:
pointer to the found element or NULL otherwise.
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[modifier] Exemple

#include <stdlib.h>
#include <stdio.h>
 
struct data {
  int nr;
  char const *value;
} dat[] = {
  {1, "Foo"}, {2, "Bar"}, {3, "Hello"}, {4, "World"}
};
 
int data_cmp(void const *lhs, void const *rhs) {
  struct data const *const l = lhs;
  struct data const *const r = rhs;
  return l->nr < r->nr;
}
 
int main(void) {
  struct data key = { .nr = 3 };
  struct data const *res = bsearch(&key, dat, sizeof(dat)/sizeof(dat[0]),
                                   sizeof(dat[0]), data_cmp);
  if(!res) {
    printf("No %d not found\n", key.nr);
  }
  else {
    printf("No %d: %s\n", res->nr, res->value);
  }
}

Résultat :

No 3: Hello

[modifier] Voir aussi

Trie une plage d'éléments de type indéterminé
Original:
sorts a range of elements with unspecified type
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(fonction) [edit]
C++ documentation for bsearch