built in sort c code example

Example: qsort in c

#include <stdlib.h>
int cmpfunc (const void * a, const void * b) {
   return ( *(int*)a - *(int*)b );
}

int main () {
//n is number of elements in arr(size f that arr)
   qsort(arr, n, sizeof(int), cmpfunc);
   }