1. qsort排序
/* qsort example */
#include <stdio.h>
#include <stdlib.h>
int values[] = { 40, 10, 100, 90, 20, 25 };
int compare (const void * a, const void * b)
{
return ( *(int*)a - *(int*)b );
}
int main ()
{
int n;
qsort (values, 6, sizeof(int), compare);
for (n=0; n<6; n++)
printf ("%d ",values[n]);
return 0;
}
Output:
10 20 25 40 90 100
2.bsearch查找：
/* bsearch example */ #include <stdio.h> #include <stdlib.h> int compareints (const void * a, const void * b) { return ( *(int*)a - *(int*)b ); } int values[] = { 10, 20, 25, 40, 90, 100 }; int main () { int * pItem; int key = 40; pItem = (int*) bsearch (&key, values, 6, sizeof (int), compareints); if (pItem!=NULL) printf ("%d is in the array.\n",*pItem); else printf ("%d is not in the array.\n",key); return 0; }Output:40 is in the array3.两者结合用法：
/* bsearch example with strings */ #include <stdio.h> #include <stdlib.h> char strvalues[][20] = {"some","example","strings","here"}; int main () { char * pItem; char key[20] = "example"; /* sort elements in array: */ qsort (strvalues, 4, 20, (int(*)(const void*,const void*)) strcmp); /* search for the key: */ pItem = (char*) bsearch (key, strvalues, 4, 20, (int(*)(const void*,const void*)) strcmp); if (pItem!=NULL) printf ("%s is in the array.\n",pItem); else printf ("%s is not in the array.\n",key); return 0; }
说明：
void qsort ( void * base, size_t num, size_t size, int ( * comparator ) ( const void *, const void * ) ); void * bsearch ( const void * key, const void * base, size_t num, size_t size, int ( * comparator ) ( const void *, const void * ) );更多请参考：http://www.cplusplus.com/reference/clibrary/cstdlib/qsort/