循环后将输入返回到相邻的输出标签以计算值

Question

I am getting the correct results but I would like to be specific with the calculated values displayed for each label that is adjacent to each input.

Currently using two line breaks & it seems to line up with inputs by luck. Program calculates book cost based on the number of pages printed:

1 - 500 pages 2 cents per page

500 - 100 pages 1.5 cents per page

1000+ pages 1 cent per page

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void btnPriceResults_Click(object sender, EventArgs e)
    {
        //VARIABLES
        double[] arrPrintPageNums = new double[3];
        double total = 0;


        //INPUTS
        arrPrintPageNums[0] = double.Parse(txtInputBook1.Text);
        arrPrintPageNums[1] = double.Parse(txtInputBook2.Text);
        arrPrintPageNums[2] = double.Parse(txtInputBook3.Text);


        //PROCESS (i = INDEX NUMBER(0 1 2 3 4))
        for (int i = 0; i < arrPrintPageNums.Length; i++)
        {
            if (arrPrintPageNums[i] > 0 && arrPrintPageNums[i] <= 500)
            {
                lblBook1Price.Text += "Print Cost: " + (arrPrintPageNums[i] * 2) + "\n\n";
                total += arrPrintPageNums[i] * 0.02;
            }
            else if (arrPrintPageNums[i] > 500 && arrPrintPageNums[i] <= 1000)
            {
                lblBook1Price.Text += "Print Cost: " + (arrPrintPageNums[i] * 1.5) + "\n\n";
                total += arrPrintPageNums[i] * 0.015;
            }
            else if (arrPrintPageNums[i] > 1000)
            {
                lblBook1Price.Text += "Print Cost: " + (arrPrintPageNums[i] * 1) + "\n\n";
                total += arrPrintPageNums[i] * 0.01;
            }
            else
            {
                lblBook1Price.Text += "ERROR! OUTSIDE PRINT RANGE" + "\n\n";
            }

        }


        //OUTPUT
        lblBookPriceTotal.Text = "Total price: " + total.ToString("C2");
    }
}

Desired result:

Book 1 Pages Input - Book 1 Total Print Cost Label

Book 2 Pages Input - Book 2 Total Print Cost Label

Book 3 Pages Input - Book 3 Total Print Cost Label

Button 'Book Print Cost' - Grand Total Print Cost Label

Answer 1

Use an array of labels that match your labels to the right of the inputs:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        bookPriceLabels = new Label[] { lblBook1Price, lblBook2Price, lblBook3Price };
    }

    private Label[] bookPriceLabels;

    private void btnPriceResults_Click(object sender, EventArgs e)
    {
        //VARIABLES
        double[] arrPrintPageNums = new double[3];
        double total = 0;


        //INPUTS
        arrPrintPageNums[0] = double.Parse(txtInputBook1.Text);
        arrPrintPageNums[1] = double.Parse(txtInputBook2.Text);
        arrPrintPageNums[2] = double.Parse(txtInputBook3.Text);

        Label[] labels = new Label


        //PROCESS (i = INDEX NUMBER(0 1 2 3 4))
        for (int i = 0; i < arrPrintPageNums.Length; i++)
        {           
            if (arrPrintPageNums[i] > 0 && arrPrintPageNums[i] <= 500)
            {
                bookPriceLabels[i].Text = "Print Cost: " + (arrPrintPageNums[i] * 2);
                total += arrPrintPageNums[i] * 0.02;
            }
            else if (arrPrintPageNums[i] > 500 && arrPrintPageNums[i] <= 1000)
            {
                bookPriceLabels[i].Text = "Print Cost: " + (arrPrintPageNums[i] * 1.5);
                total += arrPrintPageNums[i] * 0.015;
            }
            else if (arrPrintPageNums[i] > 1000)
            {
                bookPriceLabels[i].Text = "Print Cost: " + (arrPrintPageNums[i] * 1);
                total += arrPrintPageNums[i] * 0.01;
            }
            else
            {
                bookPriceLabels[i].Text = "ERROR! OUTSIDE PRINT RANGE" + "\n\n";
            }

        }


        //OUTPUT
        lblBookPriceTotal.Text = "Total price: " + total.ToString("C2");
    }
}

Answer 2

I was quite confused by the picture you supplied and the code that is posted. From the first picture it “Appears” you are using three (3) labels to the right of each text box. However the supplied code only uses one label ie.. lblBook1Price . This is confusing to use this label for book 1 for all the books. You are correct is certainly blind luck that they line up properly. Remove one of “\\n”'s in the line: lblBook1Price.Text += "Print Cost: " + (arrPrintPageNums[i] * 1) + "\\n\\n"; and it won't line up properly.

Again this seems odd and not very intuitive to others who are reading your code. One solution would be to simply use 3 different labels as the first picture shows, one for each text box. At least you are not using the book 1 label to output the book 3 costs. I hope this makes sense.

The other problem I see is user sanitation, your code wil crash if the user types in letters and not numbers. I hooked up two events to handle this. KeyPressed event to allow only numeric input and the TextChanged event if the user copy and pastes invalid text. Hope this helps.

private void button1_Click(object sender, EventArgs e) {
  updateForm();
}


private void updateForm() {
  double total = 0;
  //INPUTS
  double curCost = 0;
  curCost = GetBookCost(txtInputBook1, 0.02);
  lblBook1Price.Text = curCost.ToString("C2");
  total += curCost;

  curCost = GetBookCost(txtInputBook2, 0.015);
  lblBook2Price.Text = curCost.ToString("C2");
  total += curCost;

  curCost = GetBookCost(txtInputBook3, 0.01);
  lblBook3Price.Text = curCost.ToString("C2");
  total += curCost;

  //OUTPUT
  lblBookPriceTotal.Text = "Total price: " + total.ToString("C2");
}

private double GetBookCost(TextBox pagesText, double pricePerPage) {
  double totPages = 0;
  double.TryParse(pagesText.Text, out totPages);
  double cost = totPages * pricePerPage;
  return cost;
}



private void txtInputBook1_KeyPress(object sender, KeyPressEventArgs e) {
  KeyPressManager(sender, e);
}
private void txtInputBook2_KeyPress(object sender, KeyPressEventArgs e) {
  KeyPressManager(sender, e);
}
private void txtInputBook3_KeyPress(object sender, KeyPressEventArgs e) {
  KeyPressManager(sender, e);
}

private void KeyPressManager(object sender, KeyPressEventArgs e) {
  char keyPressed = e.KeyChar;
  if ((!char.IsDigit(keyPressed)) && (!char.IsControl(e.KeyChar))) {
    e.Handled = true;
  }
}

private void txtInputBook1_TextChanged(object sender, EventArgs e) {
  TextChangedManager(sender, e);
}
private void txtInputBook2_TextChanged(object sender, EventArgs e) {
  TextChangedManager(sender, e);
}

private void txtInputBook3_TextChanged(object sender, EventArgs e) {
  TextChangedManager(sender, e);
}

private void TextChangedManager(object sender, EventArgs e) {
  TextBox tb = (TextBox)sender;
  int userInput = 0;
  if (int.TryParse(tb.Text, out userInput)) {
    updateForm();
  } else {
    if (tb.Text != "") {
      MessageBox.Show("Invalid input for number of pages!");
      txtInputBook1.Text = "";
    }
  }
}