Searching and Printing an Array

Searching an array

*A linear search of an array (look at each element starting with first)

Linear search of an array

Linear_search_of_an_array
   Set max_num_elements to required value
   Set element_found to false
   Set index to 1

   DOWHILE(NOT element_found)AND(index <= max_num_elements)
        IF array(index)= input_value THEN
          Set element_found to true
        ELSE
          index = index + 1
        ENDIF
   ENDDO

   IF element_found THEN
       Print array (index)
   ELSE
       Print ‘value not found’, input_value
   ENDIF
END

Binary search of an array

• faster than linear search for arrays with > 25 elements
• first, sort elements into ascending sequence
• next, locate the middle element
• then determine if your element is in the first half or second
• repeat the process with the selected half of the array

Binary_search_of_an_array

   Set element_found to false
   Set low_element to 1
   Set high_element to max_num_elements

   DOWHILE (NOT element_found)
                AND(low_element <= high_element)
       index = (low_element + high_element)/2

       IF input_value = array (index)THEN
          Set element_found to true
       ELSE
          IF input_value < array (index)THEN
              high_element = index – 1
          ELSE
              low_element = index + 1
          ENDIF
       ENDIF
   ENDDO

IF element_found THEN
       Print array (index)
   ELSE
       Print "value not found", input_value
   ENDIF
END

Writing out contents of an array

• use DO loop
• start with first element
• write each element until done

Write_values_of_array
     DO index = 1 to number_of_elements
          Print array(index)
     ENDDO
END