Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Array ISYS 350 Array • An array allows you to store a group of items of the same type together. • Processing a large number of items in an array is easier than processing a large number of items stored in separate variables. Declaring a Array • Declare an array in one statement: – Type[] arrayName = new type[array size]; – Ex: • string[]empName = new string[3]; • double[] intRate = new double[6]; Array Elements • Array elements are indexed from 0 to array size – 1. • Each element can be accessed by its index: – arrayName[index] – Ex: • empName[0] • intRate[2] Array Initialization • With the declaration statement: – string[] empName = new string[3] { "Peter", "Paul", "Mary" }; – double[] intRate = new double[6] { .03, .04, .05, .06, .07, .08 }; • Initialize each element separately: – empName[0] = "Peter"; – empName[1] = "Paul"; – empName[2] = "Mary"; Accessing Array Elements with a for loop int arrayIndex; for (arrayIndex = 0; arrayIndex <= 2; ++arrayIndex) { MessageBox.Show(empName[arrayIndex].ToString()); } • Using array’s Length property: for (arrayIndex = 0; arrayIndex <= empName.Length-1; ++arrayIndex) { MessageBox.Show(empName[arrayIndex].ToString()); } Note: Length - 1 Example: Compute the sum and average of numbers in an array double[] myGPAs = new double[5] { 2.5, 3.2, 3.4, 2.9, 3.6 }; double sumGPA=0, avgGPA; for (int i = 0; i <= myGPAs.Length - 1; ++i) { sumGPA += myGPAs[i]; } avgGPA = sumGPA / myGPAs.Length; MessageBox.Show("Average GPA is: " + avgGPA); Using Array’s Methods and Length property • Sum(), Average(), Max(), Min(); double[] myGPAs = new double[5] { 2.5, 3.2, 3.4, 2.9, 3.6 }; double avgGPA, maxGPA, minGPA; avgGPA = myGPAs.Average(); maxGPA = myGPAs.Max(); minGPA=myGPAs.Min(); MessageBox.Show(“The size of array is: " + myGPAs.Length); Create a Loan Payment Form If rates are stored in an array • Method 1: Using a loop to create the Listbox with rates in the Form Load event string[] strRate = new string[6] { "3%", "4%", "5%", "6%", "7%", "8%" }; for(int i=0;i<=strRate.Length-1;i++) { listBox1.Items.Add(strRate[i]); } Method 2: Data Binding Binding an array to a control’s DataSource property • A string array to store rates with “%”: – string[] strRate = new string[6] { "3%", "4%", "5%", "6%", "7%", "8%" }; • Bind the array to a listbox: – listBox1.DataSource = strRate; • Using the Form Load event Data Binding Example private void Form1_Load(object sender, EventArgs e) { string[] strRate = new string[6] { "3%", "4%", "5%", "6%", "7%", "8%" }; listBox1.DataSource = strRate; } Parallel Array Example • A parallel array to store the numerical rates: • double[] intRate = new double[6] { .03, .04, .05, .06, .07, .08 }; • Use listbox selectedIndex to access the rate: • intRate[listBox1.SelectedIndex] Code Example double[] intRate = new double[6] { .03, .04, .05, .06, .07, .08 }; double loan, rate, term, payment; loan = double.Parse(textBox1.Text); rate = intRate[listBox1.SelectedIndex]; if (radioButton1.Checked) term = 15; else term = 30; payment = Financial.Pmt(rate / 12, term * 12, -loan); textBox2.Text = payment.ToString("c");