In .NET, how can I convert from "0.000" to a 'long'?

Question

I have a string, "0.000" (or any similar string), that I would like to convert to a long. I am happy to "chop-off" anything after the decimal.

What is the best way to go about this?

I can convert to double and then to long, but I'm just wondering if there is an easier way. All the following statements throw exceptions:

long l3 = Convert.ToInt64(nrToConvert);

long l1;
long.TryParse(nrToConvert, out l1);

long l2 = long.Parse(nrToConvert);

Answer 1

long myLong = Int64.Parse('0.000');

It can throw a System.FormatException so cater for that. There's also Int64.TryParse() if you just want it to return 0 if it can't parse.

Answer 2

Have you tried something link this:

(long)Math.Round(double.Parse("1.234"));

Of course, you should use TryParse first, but this should get you started.

Answer 3

In general when parsing a string value I would firstly parse it to the type it's representing. So in this case parse it as a double since it is a double. And yes I wrote parse not convert by intention. There's so many things that can go wrong when parsing a string so always plan for your parsing to fail! it almost certainly will at some point.

double val;
if(double.TryParse(nrToConvert,out val))
{
  //yous should validate that the value is within the expected range as well
  return (long)val;
}
else
{
  //do some error handling;
}

Answer 4

None of these will work (you'll get a "String is in the wrong format" exception, the TryParse will just fail), you need to either
1) Convert the string to a double first, then cast to a Long

long lng = (long)Convert.ToDouble(nrToConvert); 

or

2) Trim the decimal from the string and convert that (something like)

string nrToConvert =  "0.000";
nrToConvert = nrToConvert.IndexOf('.') > 0 ? nrToConvert.Substring(0, nrToConvert.IndexOf('.') ) : nrToConvert;

long lng = Convert.ToInt64(nrToConvert);

However I'd go with 1, it better refelects what you're doing (taking a double and converting that to a long)

Answer 5

As long as the fraction is zero, you can parse those strings by telling it that a decimal point is acceptable:

        long value = long.Parse("0.000", System.Globalization.NumberStyles.AllowDecimalPoint);

It will however not truncate or round numbers for you, non-zero fractions throw an exception (or fail TryParse). You need to explicitly apply the type of truncation you want:

        long value = (long)decimal.Parse("1.500");

Or use Math.Round, Truncate, Ceiling. Note that you technically should not use double.Parse(), a long has too many digits to be accurately represented by a double (19, double only supports 15 significant digits).