如何在C＃中将浮点字符串转换为int

Question

I have a string:

string test = "19,95";

and I wan't to convert it to an int.

I use:

int num = Convert.Int32(test);

However it throws an FormatException. And tells me that the string is not a proper string for conversion.

My guess is that it has to do with the decimal seperator.

How do i work around this?

Answer 1

using System.Globalization;
...
NumberFormatInfo nfi = new NumberFormatInfo();
nfi.NumberDecimalSeparator = ",";
double num = Convert.ToDouble(test, (IFormatProvider)nfi);

Tested & working.

For completeness:

int applesApplesApples = Math.Ceiling(num);
int bananaBananaBanana = (int)num;
int cucumberCucumberCucumber = Math.Floor(num);

[Update]

As Rushyo correctly pointed out in my comments below, this example is contrived and the best practice approach is to identify which culture you are working with in order to get the correct CultureInfo object to work off of.

You can then utilize the localized NumberFormatInfo from that specific CultureInfo when doing all your numeric formatting.

Answer 2

string dblText = "19,95";
CultureInfo ci = new CultureInfo ("en-US", true);
ci.NumberFormat.NumberDecimalSeparator = ",";
double dblValue = double.Parse (dblText, NumberStyles.AllowDecimalPoint, ci);

If you need 19 (casting off the decimal part):

int intValue = (int)dblValue;

If you need 20 (mathematical rounding):

int intValue = (int)(dblValue + 0.5);

Answer 3

What integer would you expect to get from "19,95" ? 1995? 19? 20?

Perhaps you should convert the number to a double first, and then round or truncate in whichever direction makes sense for your application.

Answer 4

As the others already mentioned the main problem of your question is, that you don't gave any information about what result you expect and some also brought up the problem with the Culture (decimal separator, thousand separator). So i will make a little sum up:

private int Parse(string text)
{
    Decimal value;

    //Select the culture you like to use
    var culture = CultureInfo.CurrentCulture;
    //var culture = CultureInfo.GetCultureInfo("en-US");
    //var culture = CultureInfo.GetCultureInfo("de-DE");

    if (Decimal.TryParse(text, NumberStyles.Number, culture, out value))
    {
        //Throw away the fractional part
        //return (int)value;

        //or make some rounding??
        return (int)Math.Round(value, MidpointRounding.ToEven);
    }

    //What should happen if the parsing fails??
    //Return some default value
    return int.MinValue;
    //return 0;

    //Or throw an exception?
    //throw new FormatException();
    //In that case, maybe use directly Decimal.Parse and let this
    //function throw the exception with the correct message.
}

Answer 5

are you sure you want it to be an int?

this number is a double.

int num = (int)double.Parse(test); //will be 19

double num = double.Parse(test); //wil be 19.95