Binary search:

#include <stdio.h>

int main()
{
   int c, first, last, middle, n, search, array[100];
   scanf("%d",&n);
   for (c = 0; c < n; c++)
   scanf("%d",&array[c]);
   scanf("%d", &search);
   first = 0;
   last = n - 1;
   middle = (first+last)/2;
   while (first <= last) {
      if (array[middle] < search)
         first = middle + 1;   
      else if (array[middle] == search) {
         printf("%d\n",middle+1);
         break;
      }
      else
         last = middle - 1;
      middle = (first + last)/2;
   }
   if (first > last)
      printf("Not found", search);
   return 0; 
}