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bsearch

Usage

   #include <stdlib.h>
   void *bsearch(const void *key,const void *base, size_t num,
                 size_t width,int (*cmp)(const void *elem1,
                 const void *elem2));

   ANSI

Description

   bsearch performs a binary search of a sorted array of num elements, which
   is pointed to by base, for an element which matches key. The contents of
   the array must have been previously sorted into ascending order. Each
   item of the array is width bytes. The typedef size_t is the unsigned
   integer data type that results from the use of the sizeof operator. The
   function used in the search is *cmp. This function must be supplied by
   the programmer and must be declared as taking C linkage. The cmp function
   takes two arguments as pointers to the element in the array. The *cmp
   function must return one of the following values:

           Value   Meaning
           -----   ---------------------------
           < 0     elem1 is less than elem2
           = 0     elem1 and elem2 match
           > 0     elem1 is greater then elem2

   Note that the standard library function strcmp is a suitable compare
   function (cmp) for C style strings.

Example 

   #include <stdio.h>
   #include <stdlib.h>

   #define SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
   int array[] = {1254,3427,1111,3901,6677,0101};

   #ifdef __cplusplus
   extern "C"
   #endif

   int intcmp(int *p1, int *p2)
   {
           return(*p1 - *p2);
   }

   int main()
   {
       int *pointer;

       int key = 3901;
       pointer = (int *) bsearch(&key,array,SIZE(array),
   sizeof(int),intcmp);
       if(pointer)
       {
           printf("[%d] is in array\n",key);
       }
       else
       {
           printf("[%d] is not in array\n",key);
       }
       return EXIT_SUCCESS;
   }

Return Value

   Returns a pointer to the matching element, or NULL if not found.