how to multiply numericupdown value with textbox value and show in another textbox in c#

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I am trying to multiply numericupdown value with textbox value and show it in another textbox. when i enter value in textbox and after that select value from numericupdown, then all goes well. but when i do vice-versa, it gives me error.

error: Input string was not in a correct format.

my code is

C#

public void Multiply()
        {
            int price = Convert.ToInt32(textBox3.Text);
            int quantity = Convert.ToInt32(numericUpDown1.Value);

            int total = quantity * price;
            textBox1.Text = total.ToString();
        }

        private void numericUpDown1_ValueChanged(object sender, EventArgs e)
        {
            Multiply();
        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {
            Multiply();
        }

please help

Posted 15-Feb-14 0:08am

Member 9764132

Updated 15-Feb-14 0:12am

v2

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OriginalGriff · Accepted Answer · 2014-02-15T00:15:00

Solution 1

Simple: if there is no value in your TextBox when you change the value in the NumericUpDown, then the conversion from a string will fail.
Try this instead:

C#

public void Multiply()
    {
    int price;
    if (int.TryParse(textBox3.Text, out price))
        {
        int quantity = (int)numericUpDown1.Value;
        int total = quantity * price;
        textBox1.Text = total.ToString();
        }
    }

Posted 15-Feb-14 0:15am

OriginalGriff

Comments

Member 9764132 15-Feb-14 6:21am

thanks OriginalGriff, it worked.

OriginalGriff 15-Feb-14 6:29am

You're welcome!