1. DATA STRUCTURE Presented By: Mahmoud Rafeek Alfarra Using C# MINISTRY OF EDUCATION & HIGHER EDUCATION COLLEGE OF SCIENCE AND TECHNOLOGY KHANYOUNIS- PALESTINE Information Technology, 3’rd Semester

2. Outline  Array data structure  Swapping  Sorting Arrays  Searching Arrays  Emank X Mezank !!

3. Array data structure  Arrays are data structures consisting of data items of the same type.  Arrays are “static” entities, in that they remain the same size once they are created. 3 Presented & Prepared by: Mahmoud R. Alfarra

4. Swapping  Swapping the values of two cells or variables is how to change the values with out missing data. 4 Presented & Prepared by: Mahmoud R. Alfarra AB A 1 3 str1str2 str 2 B

5. Swapping hold = firstvariable firstvariable = secondvariable secondvariable= hold 5 Presented & Prepared by: Mahmoud R. Alfarra Write a method that performs a swap operation HW 2.1

6. Sorting Arrays  Sorting data : arranging the data into some particular order, such as ascending or descending.  Sorting data is one of the most important computing applications. 6 Presented & Prepared by: Mahmoud R. Alfarra

7. Sorting data for ( int pass = 1, pass < arrayLength, pass++ ) for ( int i = 0; i < arrayLength- 1; i++ ) if ( b[ i ] > b[ i + 1 ] ) Swap(b[ i ], b[ i +1] ); 7 Presented & Prepared by: Mahmoud R. Alfarra Write a method that sort an integer array HW 2.2 Write a method that sort a string array HW 2.3 bubble sort

8. Searching Arrays  Often, programmers work with large amounts of data stored in arrays.  It might be necessary in this case to determine whether an array contains a value that matches a certain key value.  The process of locating a particular element value in an array is called searching. 8 Presented & Prepared by: Mahmoud R. Alfarra

9. Searching Arrays  We discuss two searching techniques  The linear search technique : Search element by element. Uses a for structure containing an if structure to compare each element of an array with a search key. Works well for small or unsorted arrays.  The binary search technique: The binary search algorithm eliminates half of the elements in the array being searched after each comparison. Works well for large or sorted arrays. 9 Presented & Prepared by: Mahmoud R. Alfarra

10. The linear search technique for ( int n = 0, n < arrayLength, n++ ) if ( array[ n ] == wanted) return n break the loop return -1 10 Presented & Prepared by: Mahmoud R. Alfarra Write a program to implement the linear search technique HW 2.4

11. The binary search technique 11 Presented & Prepared by: Mahmoud R. Alfarra 258188909979345556667980 12345 6 7891011 12 13 (0+13) / 2 = 6 If (array[6] == 80) return 6 Elseif (array[6] > 80) High = 6 -1 Else Low = 6+1 Middle = (low + high)/2 Wanted = 80 array 0 (7+13) / 2 = 10 If (array[10] == 80) return 10 Elseif (array[10] > 80) High = 10 -1 Else Low = 10+1 (7+9) / 2 = 8 If (array[8] == 80) return 8 Elseif (array[8] > 80) High = 8-1 Else Low = 8+1 123

12. The binary search technique 12 Presented & Prepared by: Mahmoud R. Alfarra 258188909979345556667980 12345 6 7891011 12 13 Middle = (low + high)/2 Wanted = 80 array 0 (7+9) / 2 = 8 If (array[8] == 80) return 8 Elseif (array[8] > 80) High = 8-1 Else Low = 8+1 3 (9+9) / 2 = 9 If (array[9] == 80) return 8 Elseif (array[9] > 80) High = 9-1 Else Low = 9+1 4 return 8 Using the same representation way perform the linear technique HW 2.5

13. The binary search technique int low = 0 int high = arrayLength – 1 while ( low <= high ) middle = ( low + high ) / 2 if ( key == array[ middle ] ) return middle else if ( key < array[ middle ] ) high = middle - 1 else low = middle + 1; return -1; 13 Presented & Prepared by: Mahmoud R. Alfarra Write a program to implement the binary search technique with sorted and then unsorted array HW 2.6

14. Emank X Mezank !!  قال عمر بن الخطاب رضي الله عنه‏:‏ ‏(‏ثلاث يصفين لك ود أخيك‏:‏ أن تسلم عليه إذا لقيته وتوسع له في المجلس وتدعوه بأحب أسمائه إليه‏)‏‏.‏

15. Next Lecture Insert & delete elements