我可以用lambda缩短if / else语句吗？

Question

I have the following statement as part of building a datarow for a datatable and I was wondering if I could shorten it using a lambda statement or anything more elegant.

if (outval(line.accrued_interest.ToString()) == true) 
{ 
temprow["AccruedInterest"] = line.accrued_interest; 
} 
else 
{
temprow["AccruedInterest"] = DBNull.Value;
}

The statement is checked by:

 public static bool outval(string value)
        {
            decimal outvalue;
            bool suc = decimal.TryParse(value, out outvalue);
            if (suc)
            {
                return true;
            }
            else
            {
                return false;
            }


        }

Answer 1

public static bool outval(string value)
{
    decimal outvalue;
    return decimal.TryParse(value, out outvalue);
}

temprow["AccruedInterest"] = outval(line.accrued_interest.ToString()) ? (object)line.accrued_interest : (object)DBNull.Value;

Edit: casting to object is important since ?: ternary operator needs to return results both true case and false case has to be implicitly converted to other. I don't know what is type of accrued_interest I assume it will be a double or decimal since there is no implicit conversion between decimal and DBNull . In order to make it work you've to cast to object type. Is that clear?

Answer 2

You want the ? Operator, you don't need a lambda expression.

http://msdn.microsoft.com/en-us/library/ty67wk28.aspx

int input = Convert.ToInt32(Console.ReadLine());
string classify;

// if-else construction.
if (input < 0)
    classify = "negative";
else
    classify = "positive";

// ?: conditional operator.
classify = (input < 0) ? "negative" : "positive";

Answer 3

You don't need to call a separate method. No need of method or any other things

decimal result;   
if(decimal.TryParse(line.accrued_interest.ToString(),out result))
 temprow["AccruedInterest"] = line.accrued_interest
else
 temprow["AccruedInterest"] = DBNull.Value; 

Answer 4

Also,

public static bool outval(string value)
{
    decimal outvalue;
    bool suc = decimal.TryParse(value, out outvalue);
    if (suc)
    {
        return true;
    }
    else
    {
        return false;
    }
}

To..

public static bool outval(string value)
{
    decimal outvalue;
    return decimal.TryParse(value, out outvalue);
}