bsearch_s
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Header File
stdlib.h
Category
Searching and sorting utilities
Prototype
void *bsearch_s(const void * __key, const void * __base, rsize_t __nelem, rsize_t __width, int (_USERENTRY *__fcmp)(const void *k, const void *i, void *__context), void *__context);
Description
Replaces bsearch adding security enhancements.
bsearch_s searches a table (array) of __nelem elements in memory and returns the address of the first entry in the table that matches the search key defined by __base.
The size of each element in the array is specified by __width.
The comparison function _fcmp must be used with the _USERENTRY calling convention. The array __fcmp is called on must be sorted in ascending order.
__fcmp is called with three arguments: k(the key element), y(an element in the array), and __context(that is passed directly to the __fcmp function in order to allow a more generic user implementation). __fcmp returns an integer that takes its values as follows:
- < 0 if *k < *y
- == 0 if *k == *y
- > 0 if *k > *y
Return Value
bsearch_s returns the address of the first element in the array that matches the search key. If no match is found, then bsearch_s returns null.
Example
#include <stdlib.h>
#include <stdio.h>
typedef int (*fptr)(const void*, const void*, void*);
#define NELEMS(arr) (sizeof(arr) / sizeof(arr[0]))
int numarray[] = {123, 145, 512, 627, 800, 933};
int numeric (const int *p1, const int *p2)
{
return(*p1 - *p2);
}
#pragma argsused
int lookup(int key)
{
int *itemptr;
/* The cast of (int(*)(const void *,const void*))
is needed to avoid a type mismatch error at
compile time */
itemptr = (int *) bsearch_s(&key, numarray, NELEMS(numarray),
sizeof(int), (fptr)numeric, NULL);
return (itemptr != NULL);
}
int main(void)
{
if (lookup(512))
printf("512 is in the table.\n");
else
printf("512 isn't in the table.\n");
return 0;
}
Portability
| POSIX | Win32 | ANSI C | ANSI C++ |
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