How to avoid "input string is not in correct format" error when passing a null value

Question

I have a class that I am passing a value too from my textbox. I use int? in the class I am passing too, to allow null values. Every-time I execute it gives the input string is not in correct format error. How can I get it to allow the null value? I thought about creating an if statement that just passes string = "null". I put my code below thank you in advance.

This is what I use to pass the values to my class that gives the error when I leave it blank.

newGrid.EmployeeID = Convert.ToInt32(employeeIDTextBox.Text);
newGrid.JobID = Convert.ToInt32(JobIDTextBox.Text);

Variable declaration in my class that the info is passing to.

public int? JobID { get; set; }

Dai · Accepted Answer · 2013-12-28 03:15:03Z

6

Use TryParse instead:

Int32 employeeId;
newGrid.EmployeeID = Int32.TryParse( employeeIDTextBox.Text, out employeeId ) ? employeeId : null;

This does require multiple lines of statements. You could wrap TryParse to simplfy this, like so:

public static Int32? Int32TryParseSafe(String text) {
    Int32 value;
    return Int32.TryParse( text, out value ) ? value : null;
}

// Usage:
newGrid.EmployeeID = Int32TryParseSafe( employeeIDTextBox.Text );

answered Dec 28, 2013 at 3:15

Dai

158k31 gold badges314 silver badges436 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Kpt.Khaos Over a year ago

Ok so use the second method or both?

Kpt.Khaos Over a year ago

Error 1 Type of conditional expression cannot be determined because there is no implicit conversion between 'int' and '<null>'

Kpt.Khaos Over a year ago

I got it needed (int?) ex: ? (int?)value

chiliNUT · Accepted Answer · 2013-12-28 03:15:36Z

1

      int number;
      bool result = Int32.TryParse(employeeIDTextBox.Text, out number);
      if (result)
      {
         newGrid.EmployeeID=number;       
      }
      else
      {
      //whatever you want to do for bad values
      newGrid.EmployeeID=0;
      }

answered Dec 28, 2013 at 3:15

chiliNUT

19.5k14 gold badges72 silver badges116 bronze badges

Comments

Chris Hayes · Accepted Answer · 2013-12-28 03:16:46Z

1

You won't be able to convince Convert.ToInt32 to change its behavior, but you can easily get the effect you want yourself:

string employeeID = employeeIDTextBox.Text;
newGrid.EmployeeID = string.IsNullOrEmpty(employeeID) ? null : Convert.ToInt32(employeeID);

Note that while this is less verbose than some other options, you aren't as safe as you are with TryParse. If the user enters non-numeric characters this will fail.

answered Dec 28, 2013 at 3:16

Chris Hayes

12.2k5 gold badges35 silver badges48 bronze badges

Collectives™ on Stack Overflow

How to avoid "input string is not in correct format" error when passing a null value

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related