FormatException was Unhandled ((int.parse) value from an array)

Question

I am writing a program that takes data from a 2d array in a text file containing loan information. I've finally figured out how to get into the click event for the button, and now I'm getting a "FormatException was unhandled" error when trying to declare "currentValue" by parsing the third value of the array. How can I fix this?

namespace
{
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }
    string[,] loans = new string[4, 6];
    int recordCount = 0;

    private void Form1_Load(object sender, EventArgs e)
    {
        string currentLine;
        string[] fields = new string[6];
        int row = 0;
        StreamReader loanReader = new StreamReader(@"C:\loans.txt");

        while (loanReader.EndOfStream == false)
        {
            currentLine = loanReader.ReadLine();
            fields = currentLine.Split(',');

            loans[row, 0] = fields[0];
            loans[row, 1] = fields[1];
            loans[row, 2] = fields[2];
            loans[row, 3] = fields[3];
            loans[row, 4] = fields[4];
            loans[row, 5] = fields[5];

            row = row + 1;
        }
        recordCount = row;
        loanReader.Close();
        int nbrRows = 4;
        txtPrincipal.Text = "0";

        for (int i = 0; i < nbrRows; i++)
        {
            comboBox1.Items.Add(loans[i, 0]);
        }
    }

    private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        int row = comboBox1.SelectedIndex;
        lstDisplay.Items.Clear();
        string fmtStr = "{0,-15}{1,8}{2,30}";
        string fmtStr2 = "{0,-15}{1,8:C}{2,40:C}";
        lstDisplay.Items.Add(string.Format(fmtStr, "Loan #", "Original Balance", "Current Balance"));
        lstDisplay.Items.Add(string.Format(fmtStr2, loans[row, 0], loans[row, 1], loans[row,2]));

    }

    private void btnRP_Click(object sender, EventArgs e)
    {
        int row = 0, currentLoan, interest, interestPmt, monthlyPmt, principalPmt, newBalance;
        string selection = comboBox1.SelectedItem.ToString();

        for (row = 0; row < recordCount; row++)
        {
            if (loans[row, 0] == selection)
            {
                currentLoan = int.Parse(loans[row, 2]);
                interest = int.Parse(loans[row, 3]);
                monthlyPmt = int.Parse(loans[row, 5]);

                interestPmt = currentLoan * interest / 1200;
                principalPmt = monthlyPmt - interestPmt;
                newBalance = currentLoan - principalPmt;
                loans[row, 2] = newBalance.ToString();

                lstDisplay.Items.Clear();
                string fmtStr = "{0,-15}{1,8}{2,30}";
                string fmtStr2 = "{0,-15}{1,8:C}{2,40:C}";
                lstDisplay.Items.Add(string.Format(fmtStr, "Loan #", "Original Balance", "Current Balance"));
                lstDisplay.Items.Add(string.Format(fmtStr2, loans[row, 0], loans[row, 1], loans[row, 2]));
            }
        }

    }

Answer 1

You're problem is a whole lot easier to fix with some clean up.

step 1: Make a Loan class that has properties for all the pieces of data about the loan - loan number, loan amount, interest, etc.

step 2: replace string[,] loans = new string[4, 6]; with List<Loan> MyLoans;

step 3: Make a function that binds the combobox with the list of MyLoans using the loan number as the datavalue and the amount or whatever as the displayvalue

step 4: On page load read each line from your text file creating a Loan object and adding it MyLoans. Call the binding function you created in step 3.

step 5: on the button click forget about the selected index. use the datavalue from the selected item. Locate this loan in MyLoans and subtract the payment from it.

step 6: call the bind function one more time now that you've updated MyLoans - it should bind with the new information.