Newbie here - a few questions..

[Even92LN]

Hello everyone! I'm working on my very first program ever, it's a calculator for (flightsim) pilots that calculates how fast you need to descend in order to reach your target at the altitude you want.

Here's what it looks like right now..


It works very well, but there are a few functions I want to add before I release it. I have managed to make it accept only numerous input and backspace, and if you write alphabetic letters, "Only numbers allowed" pops up.

BUT when I leave one or more text-boxes empty and press calculate, it crashes. What I need is a popup that says I have to write something in the input fields. How should I do that?

I also want to add some tooltips that pops up when I move the mouse cursor over the text fields. But again - how?

Would be very nice if some of you could help me, but keep in mind that I'm completely new to this and it's my first day of programming something. So please try to explain in an "easy" way...

Greets,
Even

[Even92LN]

Oh, forgot to post the picture of it.. here:

[BigEd781]

Sounds like an annoying design to me. How about this?

1. Instead of showing a popup when the user enters invalid data (which is extremely annoying...), don't allow it to begin with. Use a masked textbox or handle the KeyPress event yourself and filter out invalid data.

2. Simply disable the "Calculate" button until all data is valid. You can do this easily by updating the Enabled property from within an Application.Idle event handler (WinForms) or by binding the IsEnabled property of the button to a set of properties using a custom converter (WPF)

[someuser77]

when I leave one or more text-boxes empty and press calculate, it crashes. What I need is a popup that says I have to write something in the input fields. How should I do that?

Assuming you are using Visual Studio, try to use the debugger to find out what went wrong or attach the project to a message so we can take a look at the code. You will probably need to test for a non empty text box value using its Text (!= String.Empty) or Text.Length ( > 0) property before trying to test if it contains chars.

Walkthrough: Debugging a Windows Form

Visual Studio Debugging Tutorial

I also want to add some tooltips that pops up when I move the mouse cursor over the text fields. But again - how?

Consider using the ToolTip Class.

[fcronin]

I like using the numeric up/down control, as it forces numeric entry for you, you can set a larger increment so values will 'spin-up' faster for the user, and will let you assing a min and max value... one thing that annoys me about it however is that is doesnt take a default value if a user leaves it blank... but it gives a good starting point for numeric input in my opinion.

[Even92LN]

Thanks for your replies! Will look futher into it tomorrow. Btw, here's what my file looks like now:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication5
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void label2_Click(object sender, EventArgs e)
        {

        }

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void label3_Click(object sender, EventArgs e)
        {

        }

        private void label5_Click(object sender, EventArgs e)
        {

        }

        private void label6_Click(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            {
                if (textBox2.Text == "")
                {
                    MessageBox.Show("Only numbers allowed");
                }
                int dist = int.Parse(textBox1.Text);
                int cAlt = int.Parse(textBox2.Text);
                int tAlt = int.Parse(textBox3.Text);
                int spd = int.Parse(textBox4.Text);
                int vs;
                vs = -((cAlt - tAlt) * spd) / (dist * 60);

                textBox5.Text = vs.ToString();
            }
        }
        

        private void textBox2_TextChanged(object sender, EventArgs e)
        {

        }

        private void button2_Click(object sender, EventArgs e)
        {
            textBox1.Text = "";
            textBox2.Text = "";
            textBox3.Text = "";
            textBox4.Text = "";
            textBox5.Text = "";

        }

        private void textBox5_TextChanged(object sender, EventArgs e)
        {

            textBox5.ReadOnly = true;

        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            
        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox4_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            { //accept only numbers and back space.
                if ((e.KeyChar < '0' || e.KeyChar > '9') && (e.KeyChar != '\b'))
                {
                    MessageBox.Show("Only numbers allowed");
                    e.Handled = true;
                }
                else
                {
                    e.Handled = false;
                }

            } 

            }

        private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
        {
            { //accept only numbers and back space.
                if ((e.KeyChar < '0' || e.KeyChar > '9') && (e.KeyChar != '\b'))
                {
                    MessageBox.Show("Only numbers allowed");
                    e.Handled = true;
                }
                else
                {
                    e.Handled = false;
                }

            } 
        }

        private void textBox3_KeyPress(object sender, KeyPressEventArgs e)
        {
            { //accept only numbers and back space.
                if ((e.KeyChar < '0' || e.KeyChar > '9') && (e.KeyChar != '\b'))
                {
                    MessageBox.Show("Only numbers allowed");
                    e.Handled = true;
                }
                else
                {
                    e.Handled = false;
                }

            } 
        }

        private void textBox4_KeyPress(object sender, KeyPressEventArgs e)
        {
            { //accept only numbers and back space.
                if ((e.KeyChar < '0' || e.KeyChar > '9') && (e.KeyChar != '\b'))
                {
                    MessageBox.Show("Only numbers allowed");
                    e.Handled = true;
                }
                else
                {
                    e.Handled = false;
                }

            } 
        }

        private void chart1_Click(object sender, EventArgs e)
        {

        }

        private void toolTip1_Popup(object sender, PopupEventArgs e)
        {
            

        }

        private void label11_Click(object sender, EventArgs e)
        {

        }

        private void toolTip1_Popup_1(object sender, PopupEventArgs e)
        {
            ToolTip toolTip1 = new ToolTip();
            toolTip1.ShowAlways = true;
            toolTip1.SetToolTip(textBox1, "Click me to execute.");

        }

        private void toolTip1_Draw(object sender, DrawToolTipEventArgs e)
        {

        }

        private void label12_Click(object sender, EventArgs e)
        {

        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void toolTip1_Popup_2(object sender, PopupEventArgs e)
        {

        }
        }
    }

[BigEd781]

If you are going to allow invalid data (which you shouldn't) then you should be using int.TryParse instead of int.Parse. Currently you only check for an empty string and this is why you are crashing (one reason anyway).

[Even92LN]

Ok, I tried to do what BigEd suggested; to disable the caclulate button until the fields had a valid value. I can't say I understood much of what you wrote, BigEd (sorry, but I'm VERY new to this...) but I found this, which looked like a perfect coding for what I was trying to do: http://stackoverflow.com/questions/4...box-is-valid-c

So I tried to use that and wrote this in my project file:

        private void textBox6_TextChanged(object sender, EventArgs e)
        {
            this.button3.Enabled = !string.IsNullOrEmpty(this.textBox6.Text);
        }

Here's a picture (I have added some new functions): (EDIT: I know, should be "pounds")

textBox6 = the top text box
button3 = the first calculate button

No errors, but when I start the program the button is still enabled. BUT if I write something and clear it again, either using backspace or the "clear fields" button, it gets disabled. And when I write somtehing again it enables like it should. What can I do to fix this, so the button is disabled from the program startup?


Thanks...

[Ubiquitous]

You can disable the button 2 ways that I can think of. First one method is when you click the button in its properties there will be one called (Enabled) set it to false and it will start the application with the button disabled.

The second method is clicking the form twice which will give you a form_load and inside this method you add button3.Enabled = false; This will run when the application loads and will disable your button at the beginning.

[BigEd781]

The problem is that the TextChanged event is not being fired initially.

What I would do for a small WinForms project is like so:

public class Form1 : Form
{
    public Form1()
    {
        Application.Idle += Application_Idle;
    }
   
    private void Application_Idle( object sender, EventArgs e )
    {
        button3.Enabled = !String.IsNullOrWhiteSpace(textBox6.Text);
    }
}

I would also recommend giving meaningful names to your controls

[Even92LN]

Thanks a lot everyone, working well now!

Have worked a little more on the application, and I must say I'm quite surprised by what I have achieved so far But I wonder how I can get the time format in "HH:MM" instead of "decimal-hours" in the "Scheduled flight time" textbox:


This is the "Calculate" button at the moment:

        private void calcTimeButton_Click(object sender, EventArgs e)
        {
            double fdist = int.Parse(FlightDist.Text);
            double aspd = int.Parse(GroundSpeed.Text);
            double ft;

            ft = Math.Round((fdist / aspd), 2);

            FlightTime.Text = ft.ToString();

        }

// fdist = Flight distance
// aspd = average ground speed
// ft = scheduled Flight Time

[fcronin]

Got this from stackoverflow site... I didn't bother trying it or anything...

int hours = (int)hoursDecimal;
decimal minutesDecimal = ((hoursDecimal - hours) * 60);
int minutes = (int)minutesDecimal;
int seconds = (int)((minutesDecimal - minutes) * 60);

Once you have that, I would just format it using

String.Format("{0}:{1}.{2}", hours, minutes, seconds);

[BigEd781]

Just use the DateTime or TimeSpan class, let them do the work for you.

[fcronin]

Kudos BigEd... wasn't thinking TimeSpan had an option to take in the decimal form...

                TimeSpan ts = TimeSpan.FromHours(2.5);
                Console.WriteLine(String.Format("{0}:{1}", ts.Hours, ts.Minutes));