Autoincrement textbox on button click

Question

1.00/5 (2 votes)

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System.FormatException: 'Input string was not in a correct format.'

when i click button itz showing this error . i want to increment textbox3.Text on each button click

What I have tried:

<pre>foreach (string i in listBox1.Items)
                        {
                            if (i == content)
                            {
                                MessageBox.Show("already there");
                                isValid = false;
                                textBox3.Text = "0";
                            }
                            
                        }
                        if (isValid)
                        {
                            listBox1.Items.Add(content);
                            a = Convert.ToInt32(content.ToString());
                            a++;
                            textBox3.Text = a.ToString();
                            
                        }

Posted 23-May-21 23:23pm

Member 15212425

Updated 24-May-21 1:08am

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Comments

Richard MacCutchan 24-May-21 6:09am

Use the debugger to see what is returned by content.ToString().

BillWoodruff 25-May-21 10:54am

your code makes no sense: you are iterating the ListBox Items, and, at the same time, adding new Items: that's an error right there.

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Sandeep Mewara · Answer 1 · 2021-05-24T01:08:00

C#

a = Convert.ToInt32(content.ToString());

Mostly you are trying to convert an empty string or a string which is not an integer.

Quote:
A FormatException exception can be thrown for one of the following reasons:

- In a call to a method that converts a string to some other data type, the string doesn't conform to the required pattern.
- A type implements the IFormattable interface, which supports format strings that define how an object is converted to its string representation, and an invalid format string is used.

For more details, refer: FormatException Class (System) | Microsoft Docs[^]