Answer 1

Found this for you the words array must be sorted prior to passing to search function.

void search(char string[][20],int n,char word[])
{
    int lb, mid, ub;
    lb = 0;                             //lower bound to 0
    ub = n;                             //upper bound to n
    do
    {
        mid = (lb + ub) / 2;             //finding the mid of the array
        if ((strcmp(word,string[mid]))<0)       //compare the word with mid
            ub = mid - 1;                          //if small then decrement ub
        else if ((strcmp(word,string[mid]))>0)
            lb = mid + 1;                          //if greater then increment lb
     /*repeat the process till lb doesn't becomes ub and string is found */   
    } while ((strcmp(word,string[mid])!=0) && lb <= ub);
    if ((strcmp(word,string[mid]))==0)              //if string is found
          printf("SEARCH SUCCESSFUL \n");
    else                                        //if not found
          printf("SEARCH FAILED \n");
}