• C

Search for the position of a name in the array using a recursive binary search

I have written a program that takes an array of twenty strings, sorts then in ascending ASCII order using selection sort and then searches for the position of the name in the array using a recursive binary search.  Upon compiling I receive the following error message: warning: passing arg 3 of `search' from incompatible pointer type.  Can you please help me determine the correct pointer type for the program to compile?  The program is to read the strings from a file but I have initalized the array within main for the time being.

The program is as follows:

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

#define NUMWORDS 20
#define LENWORDS 25

void displayName (void);
int search (int start, int end, char *words [], const char s[]);

//Main controls the

int main (int argc, char *argv[])
   FILE *infptr;
   char words [NUMWORDS][LENWORDS] =
   int i,j,k;
   int currMin=0;
   char temp[NUMWORDS];
   int result;
   char searchWord [LENWORDS];
   if (argc <= 1)
     printf("\nNot enough command line arguments.\n");
   infptr = fopen (argv [1], "r");
   if ((infptr)==NULL)
      printf("\nERROR: Unable to open data for reading.\n\n");
   if ((argc>=2) && ((infptr)!=NULL))
      displayName ();
      for (j=0; j < 19; j++)
         for (k=j+1; k < 20; k++)
            if (strcmp(words[currMin], words[k])>0)
         strcpy(temp, words[currMin]);
         strcpy(words[currMin], words [j]);
      for (i=0; i < NUMWORDS; i++)
         printf ("\n%d: %s", i, words[i]);
         printf ("\n\n");

         printf("Please enter a word to search (or quit to stop): ");
         scanf ("%s", searchWord);
         result = search (0, NUMWORDS - 1, words, searchWord);
         printf("The word \"%s\"", searchWord);
         if (result == -1)
            printf ("was not found.\n");
         printf ("was found at position %d.\n", result);
   //Format and finish.
   printf ("\n");
   return 0;

//The name of the programmer is displayed.
void displayName (void)
   printf("\nName: Chandra Parr\n\n");

int search (int start, int end, char *words [], const char s[])
   int middle, cmpRes;
   if (start > end)
      return (-1);
   else if (start == end)
      if (strcmp(words[start], s) == 0)
         return start;
         return (-1);
      middle = (start + end) / 2;
      cmpRes = strcmp(words[middle],s);
      if (cmpRes == 0)
         return middle;
      else if (cmpRes > 0)
         return search(start, middle - 1, words, s);
         return search (middle + 1, end, words, s);
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Kent OlsenData Warehouse Architect / DBACommented:
Hi csunnypl2,

The problem is the third parameter to search:

>> int search (int start, int end, char *words [], const char s[])

>>         result = search (0, NUMWORDS - 1, words, searchWord);

"char *words[]" signifies an array of character pointers, just as does "char **words".
"char words[NUMWORDS][LENWORDS]" signifies a single block of memory this is logically configured as a matrix with each "row" containing a string.

You'll need to change the parameter to search, or change the definition of word[][]/

Good Luck!

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