Convert string array value to int when empty string value is possible

Question

I am having trouble converting a value in a string array to int since the value could possibly be null.

StreamReader reader = File.OpenText(filePath);
string currentLine = reader.ReadLine();
string[] splitLine = currentLine.Split(new char[] { '|' });
object.intValue = Convert.ToInt32(splitLine[10]);

This works great except for when splitLine[10] is null.
An error is thrown: `System.FormatException: Input string was not in a correct format.

Can someone provide me with some advice as to what the best approach in handling this would be?

Answer 1

Don't use convert, it is better to use int.TryParse()

eg

int val = 0;
if (int.TryParse(splitLine[10], out val))
   obj.intValue = val;

Answer 2

You can use a TryParse method:

int value;
if(Int32.TryParse(splitLine[10], out value))
{
    object.intValue = value;
} 
else 
{
    // Do something with incorrect parse value
}

Answer 3

if (splitLine[10] != null)
    object.intValue = Convert.ToInt32(splitLine[10]);
else
    //do something else, if you want

You might also want to check that splitLine.Length > 10 before getting splitLine[10] .

If you're reading something like a CSV file, and there's a chance it could be somewhat complicated, such as reading multiple values, it probably will make sense for you to use a connection string or other library-sorta-thing to read your file. Get example connection strings from http://www.connectionstrings.com/textfile , using Delimited(|) to specify your delimiter, and then use them like using (var conn = new OleDbConnection(connectionString)) . See the section in http://www.codeproject.com/Articles/27802/Using-OleDb-to-Import-Text-Files-tab-CSV-custom about using the Jet engine.

Answer 4

if you're looking for the least code to write, try

object.intValue = Convert.ToInt32(splitLine[10] ?? "0");

If you want to preserve the meaning of the null in splitLine[10] , then you will need to change the type of intValue to be of type Nullable<Int32> , and then you can assign null to it. That's going to represent a lot more work, but that is the best way to use null values with value types like integers, regardless of how you get them.

Answer 5

我会去

object.intValue = int.Parse(splitLine[10] ?? "<int value you want>");