bsearch
Defined in header
<stdlib.h>
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Finds an element equal to element pointed to by key
in a sorted array pointed to by ptr
. The array contains count
elements of size
bytes. The elements are compared using function pointed to by comp
.
The behavior is undefined if the array is not already sorted in ascending order according to the same criterion that comp
uses.
If the array contains several elements that comp
would indicate as equal to the element searched for, then it is undefined which element the function will return as the result.
Contents |
[edit] Parameters
key | - | pointer to the element to search for |
ptr | - | pointer to the array to examine |
count | - | number of element in the array |
size | - | size of each element in the array in bytes |
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. int cmp(const void *a, const void *b); The function must not modify the objects passed to it. |
[edit] Return value
Pointer to the found element or NULL if such element has not been found.
[edit] Example
#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); } }
Output:
No 3: Hello
[edit] See also
sorts a range of elements with unspecified type (function) |
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C++ documentation for bsearch
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