What is the best way to take a string which can be empty or contain "1.2" for example, and convert it to an integer? int.TryParse fails, of course, and I don't want to use float.TryParse and then convert to int.
7 Answers
Solution 1: Convert.ToDouble (culture-dependent)
You may use Convert.ToDouble. But, beware! The below solution will work only when the number separator in the current culture's setting is a period character.
var a = (int)Convert.ToDouble("1.2");
Solution 2: Convert.ToDouble (culture-independent)
It's preferable to use IFormatProvider and convert the number in an independent way from the current culture settings:
var a = (int)Convert.ToDouble("1.2", CultureInfo.InvariantCulture.NumberFormat);
Solution 3: Parse & Split
Another way to accomplish this task is to use Split on parsed string:
var a = int.Parse("1.2".Split('.')[0]);
Or:
var a = int.Parse("1.2".Split('.').First());
Notes
- If you want to handle empty and null strings, write a method and add string.
IsNullOrEmptycondition. - To get decimal separator for the current culture setting, you can use
NumberFormatInfo.NumberDecimalSeparatorproperty. - You should also keep eye on rounding to avoid traps.
- Select casting,
Parse,TryParseorConvertclass wisely. Read more at:
1 Comment
MarkJ
+1. Especially for saying that
Convert.ToDouble uses the decimal delimiter from the thread culture settings (by default the Windows regional settings), and it can be a comma. You can force it to use a dot by passing CultureInfo.InvariantCulture.NumberFormatI don't know what's wrong with parsing to a float and converting to an int. I doubt that any other way would be more efficient but here's an attempt:
//allows empty strings and floating point values
int ParseInt(string s, bool alwaysRoundDown = false)
{
//converts null/empty strings to zero
if (string.IsNullOrEmpty(s)) return 0;
if (!s.Contains(".")) return int.Parse(s);
string parts = s.Split(".");
int i = int.Parse(parts[0]);
if (alwaysRoundDown || parts.Length==1) return i;
int digitAfterPoint = int.Parse(parts[1][0]);
return (digitAfterPoint < 5) ? i : i+1;
}
In order to globalize the code you would need to replace "." with System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator.
3 Comments
MarkJ
Don't forget that the decimal delimiter can be different depending on regional settings.
Mark Cidade
I added a note about globalization. Thanks!
Kangkan
Undoubtedly the best one, @Mark. +1 from my side.
int a = (int)Math.Round(float.Parse("0.9"));
You need to round it first unless you want 0.9f being converted to 0 instead of 1.
Comments
Maybe you can try to delete everything after floating point using string functions and then convert to int. But seriously I don't think it's better than converting to float and then to int.
I think another way of doing it would be splitting the string into pieces taking the decimal (.) as the delimiter and then parsing for the integer. Of course, I am yet to ask you if the string might contain values like "37.56 miles in 32.65 seconds" type values.
Considering there will be only one value (string or number) in the string, I can think of something in the following line:
public int64 GetInt64(string input)
{
if (string.IsNullOrEmpty(input)) return 0;
// Split string on decimal (.)
// ... This will separate all the digits.
//
string[] words = input.Split('.');
return int.Parse(words[0]);
}
1 Comment
btlog
Perhaps no need for int64 return when doing an int32 parse.
You can use the Visual Basic runtime Library to accomplish this from c#.
You need to add a reference to the assembly Microsoft.VisualBasic.dll to your solution.
Then the following code will do your conversion:
using VB = Microsoft.VisualBasic.CompilerServices;
class Program
{
static void Main(string[] args)
{
int i = VB.Conversions.ToInteger("1.2");
}
}
Comments
I had this same problem and ended up using a hybrid of Mark's and Dariusz':
if (num == "")
{
num = "0.00";
}
var num1 = (float)Convert.ToDouble(num);
(int)float.Parse("1.2")- it isn't too much work. Ruby does this though -"1.234".to_iyields 1Int("1.234")yields 1. But the question is about C#.Int(1.000000)returns1000000as integer result (might have to do with the fact, that in my country,is the default separator, but still worth noting). Edit: Convert.ToDouble does the same, so this is "just" an issue with the Culture-NumberFormat ...