_        _
| 45 77 93 |
| 78 79 85 |
| 72 96 77 |
‾‾        ‾‾

1. Search for the value 77. What output is produced?
   
   
   
2. Search for the value 99. What output is produced?
   
   
   
3. Try searching for other values and/or with another matrix. Try enough to show that your testing has turned up an error. Record what input you used and the resulting output.
   
   
   

The function that does the searching in the program in A is as follows:

/* MatrixSearch searches the entries of the n X n matrix
 * mat in rowwise order for an entry equal to item.
 *
 * Receive: Matrix mat, integers n and item
 * Return:  true if item is found in mat, false otherwise
 ****************************************************************/

bool MatrixSearch(Matrix mat, int n, int item)
{

  bool found;                                     // 1
  for (int row = 0; row < n; row++)               // 2
    for (int col = 0; col < n; col++)             // 3
      if (mat[row][col] == item)                  // 4
        found = true;                             // 5
      else                                        // 6
        found = false;                            // 7
  return found;                                   // 8
}

1. Complete the following trace table using item = 77 and

   
          _        _
         | 45 77 93 |
   mat = | 78 79 85 |
         | 72 96 77 |
         ‾‾        ‾‾
   

   Statement #	row	col	mat[row][col]	found
   1	?	?	?	? (? = undefined)
   2	0	?	?	?
   3	0	0	45	?
   4,7	0	0	45	false
   3	0	1	77	false
   4,5	0	1	77	true
   3	0	2
   4,_____

2. Complete the following trace table using item = one of the values you used in A that showed the program was not correct and

   
          _        _
         | 45 77 93 |
   mat = | 78 79 85 |
         | 72 96 77 |
         ‾‾        ‾‾
   

   Statement #	row	col	mat[row][col]	found
   1	?	?	?	? (? = undefined)
   2	0	?	?	?
   3	0	0	45	?
   4,_____	0	0	45
   3	0	1	77
   4,_____	0	1	77
   3	0	2
   4,_____

3. After tracing the preceding function, it should be clear why the program fails to produce the correct output. What's wrong?
   
   
   
   
   
4. If we replace the function MatrixSearch() with the following, then the program is correct, but it is not a good solution to the problem of searching a matrix. Why isn't it? (Consider the efficiency.)

   
   /* MatrixSearch searches the entries of the n X n matrix
    * mat in rowwise order for an entry equal to item.
    *
    * Receive: Matrix mat, integers n and item
    * Return:  true if item is found in mat, false otherwise
    ****************************************************************/
   
   bool MatrixSearch(Matrix mat, int n, int item)
   {
   
     bool found = false;
       for (int row = 0; row < n; row++)  
         for (int col = 0; col < n; col++)
           if (mat[row][col] == item)     
             found = true;                
     return found;                      
   }
   

   
   
   
   
5. Show how the preceding function MatrixSearch() can easily be modified to produce a good solution to the problem of searching a matrix.
   
   
   
   
   

Hand In: This lab handout with the answers filled in attached to a listing of your final Makefile
(use the enscript command from your Programming Style Sheet to print it out:
enscript -E -G -2rj -M Letter -PECT2_PS <filename>. You can also use a2ps as in: a2ps <filename>).