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CS12ex Array Processing Example |
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This project is used to demonstrate array declaration, loading, and processing. Creating and submitting the example project
is not required, but students may download and expand the self-extracting CS12ex archive into their own workspace if they like.
The data file cs12ex.txt is stored in the default folder, which is
in the project's Debug folder within the bin folder.
Folder path: CS12ex > bin > Debug
The data file contains the following :
Sample Form:Smith 88 Johnson 95 Lopez 85 Sailor 75 Davis 65 Jones 55
Source Code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
//Project: CS12ex Array Processing
//Programmer: Juan Marquez
//Description: Load a list of Students and Percentage points from a file.
// Lookup the percentage to get a letter grade.
// Display the data in list boxes.
// Data can sorted by Name or Percent and searched by name.
//
// Need System.IO for FileStream and StreamReader
using System.IO; // FileStream and StreamReader
namespace CS12ex
{
public partial class frmCS12ex : Form
{
public frmCS12ex()
{
InitializeComponent();
}
//Declare class-level arrays
const int cintARRAY_SIZE = 9; //used to declare arrays
string[] cstrName = new string[cintARRAY_SIZE];
decimal[] cdecPercent = new decimal[cintARRAY_SIZE];
string[] cstrGrade = new string[cintARRAY_SIZE];
//Use cintNumberOfStudents to process arrays because arrays
//may be partially loaded. Count set in LoadArrays.
int cintNumberOfStudents;
//Declare constant arrays
//Size of array determined by the number of values provided.
//Note the values are enclosed in braces and not parenthesis.
decimal[] cdecPERCENT_RANGE = new decimal[] { 90M, 80M, 70M, 60M, 0M };
string[] cstrLETTER_GRADE = new string[] { "A", "B", "C", "D", "F" };
private void btnLoadArrays_Click(object sender, EventArgs e)
{
int i = 0; // subscript initialized to zero
//Note:
//cstrName.Length is the number of entries that can be loaded.
//The last valid subscript value is one less than Length.
//cstrName.GetUpperBound(0) is last valid subscript value.
//In this example:
// cstrName.Length = 10
// cstrName.GetUpperBound(0) = 9
try
{
//Load the arrays with the data in the file
FileStream studentFile = new FileStream("cs12ex.txt", FileMode.Open);
StreamReader studentStreamReader = new StreamReader(studentFile);
while (studentStreamReader.Peek() != -1)
{
if (i < cstrName.Length)
{
cstrName[i] = studentStreamReader.ReadLine();
cdecPercent[i] = decimal.Parse(studentStreamReader.ReadLine());
i++; //Increment subscript by one
}
else
{
MessageBox.Show
("Error: Notify Programmer Array Size Exceeded. ",
"Array Size Exceeded", MessageBoxButtons.OK,
MessageBoxIcon.Exclamation);
break; //Get of out of loop; Arrays are full.
}//End If
}//End Loop
studentFile.Close(); //Close file
}
catch (Exception ex)
{
MessageBox.Show("Error Opening File. Data not loaded " + ex.Message,
"File Not Found",
MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
cintNumberOfStudents = i; //Save how many students were loaded
assignLetterGrade(); //assign Letter Grade
displayArrays(); //display arrays in list boxes
btnLoadArrays.Enabled = false; //Load array only once
}
void assignLetterGrade()
{
int s;
int g;
//Use cintNumberOfStudents to process a partially filled array
//cintNumberOfStudents is like Length, so we need to subtract one
//to get the subscript value of the last entry.
//outer loop walks through students
//inner loop looks up letter grade
for (s = 0; s < cintNumberOfStudents; s++)
{
for (g = 0; g <= cdecPERCENT_RANGE.GetUpperBound(0); g++)
{
if (cdecPercent[s] >= cdecPERCENT_RANGE[g])
{
cstrGrade[s] = cstrLETTER_GRADE[g];
break; //exit inner for loop
}
}//next g - percentage
}//next s - student
}
void displayArrays()
{
int i;
//In the default font, the Letter L and the number One
//look very similar - L = l, One = 1.
//Listbox names beging with the letter L, and
//not with the number one.
//Listboxes need to be cleared because this procedure
//is also called to redisplayed the data.
lstName.Items.Clear();
lstPercent.Items.Clear();
lstGrade.Items.Clear();
//Use cintNumberOfStudents to process a partially filled array
//cintNumberOfStudents is like Length, so we need to subtract one
//to get the subscript value of the last entry.
for (i = 0; i < cintNumberOfStudents; i++)
{
lstName.Items.Add(cstrName[i]);
lstPercent.Items.Add(cdecPercent[i].ToString("N0")); //N-zero
lstGrade.Items.Add(cstrGrade[i]);
}//next i - student
}
private void btnSortByName_Click(object sender, EventArgs e)
{
//Activate code below to test bubble sort
//bubbleSortName()
//return;
//Sort by name using a Simple Selection sort
int i;
int i2;
string strMinName;
int intMinSubscript;
//outer loop keeps track of where the next value
//should be placed.
for (i = 0; i < cintNumberOfStudents - 1; i++)
{
intMinSubscript = i;
strMinName = cstrName[i];
//inner loop finds the lowest value to move up
for (i2 = i + 1; i2 < cintNumberOfStudents; i2++)
{
//Only == and != can be used with strings, use CompareTo
if (cstrName[i2].CompareTo(strMinName) < 0)
{
//save the new low value found
strMinName = cstrName[i2];
intMinSubscript = i2;
}
}//next i2
swapArrayValues(i, intMinSubscript);
}//next i
//display arrays in list boxes
displayArrays();
}
void swapArrayValues(int i, int intMinSubscript)
{
//With parallel arrays, all corresponding data must be
//swapped across arrays so that all associated data
//stays on the same row.
string strHoldValue;
decimal decHoldValue;
strHoldValue = cstrName[i];
cstrName[i] = cstrName[intMinSubscript];
cstrName[intMinSubscript] = strHoldValue;
decHoldValue = cdecPercent[i];
cdecPercent[i] = cdecPercent[intMinSubscript];
cdecPercent[intMinSubscript] = decHoldValue;
strHoldValue = cstrGrade[i];
cstrGrade[i] = cstrGrade[intMinSubscript];
cstrGrade[intMinSubscript] = strHoldValue;
}
private void btnSortByPercent_Click(object sender, EventArgs e)
{
//Sort by percent using a Simple Selection sort
int i;
int i2;
decimal decMinPercent;
int intMinSubscript;
//outer loop keeps track of where the next value
//should be placed.
for (i = 0; i < cintNumberOfStudents - 1; i++)
{
intMinSubscript = i;
decMinPercent = cdecPercent[i];
//inner loop finds the lowest value to move up
for (i2 = i + 1; i2 < cintNumberOfStudents; i2++)
{
//CompareTo is NOT used with numbers
if (cdecPercent[i2] < decMinPercent)
{
//save the new low value found
decMinPercent = cdecPercent[i2];
intMinSubscript = i2;
}
}//next i2
swapArrayValues(i, intMinSubscript);
}//next i
//display arrays in list boxes
displayArrays();
}
private void btnSearchByName_Click(object sender, EventArgs e)
{
//Early exit - an early exit from a search can occur when we know that
//the value we are looking for will not be found in the array. To
//implement an early exit, the array most be sorted ascending.
//If we can determine that a value will not be found, we should
//not search the remainder of the array.
int i;
bool blnNameFound = false;
//array must be sorted ascending for early exit logic to work
btnSortByName_Click(sender, e);
//Clear message box
txtSearchResults.Clear();
for (i = 0; i < cintNumberOfStudents; i++)
{
if (txtSearchName.Text.ToUpper() == cstrName[i].ToUpper())
{
blnNameFound = true;
txtSearchResults.Text = "Matching name is selected in list box.";
lstName.SelectedIndex = i;
lstPercent.SelectedIndex = i;
lstGrade.SelectedIndex = i;
break; //exit for loop
}
else if (txtSearchName.Text.ToUpper().CompareTo(cstrName[i].ToUpper()) < 0)
{
txtSearchResults.Text = "Match not found - Early Exit taken";
break; //exit for loop
}//end if
}//next i
if (blnNameFound == false
&& txtSearchResults.Text == "")
txtSearchResults.Text = "Match not found - Reached end of array";
}
private void btnExit_Click(object sender, EventArgs e)
{
this.Close();
}
}//end of class
}//end of namespace
Revised: 11/17/2009 - www.mesacc.edu/~marquez/cis162ad/cs12ex_arrays.html