Best way to convert string to decimal separator “.” and “,” insensitive way?

Question

Application deals with strings that represent decimals that come from different cultures. For example \"1.1 and \"1,1\" is the same value.

I played with Deci

Answer 1

Below is my implementation, any good idear?

/// 

/// 
/// 
public static class NumberExtensions
{
    /// 

    /// Convert string value to decimal ignore the culture.
    /// 
    /// The value.
    /// Decimal value.
    public static decimal ToDecimal ( this string value )
    {
        decimal number;
        string tempValue = value;

        var punctuation = value.Where ( x => char.IsPunctuation ( x ) ).Distinct ( );
        int count = punctuation.Count ( );

        NumberFormatInfo format = CultureInfo.InvariantCulture.NumberFormat;
        switch ( count )
        {
            case 0:
                break;
            case 1:
                tempValue = value.Replace ( ",", "." );
                break;
            case 2:
                if ( punctuation.ElementAt ( 0 ) == '.' )
                    tempValue = value.SwapChar ( '.', ',' );
                break;
            default:
                throw new InvalidCastException ( );
        }

        number = decimal.Parse ( tempValue, format );
        return number;
    }
    /// 

    /// Swaps the char.
    /// 
    /// The value.
    /// From.
    /// To.
    /// 
    public static string SwapChar ( this string value, char from, char to )
    {
        if ( value == null )
            throw new ArgumentNullException ( "value" );

        StringBuilder builder = new StringBuilder ( );

        foreach ( var item in value )
        {
            char c = item;
            if ( c == from )
                c = to;
            else if ( c == to )
                c = from;

            builder.Append ( c );
        }
        return builder.ToString ( );
    }
}

[TestClass]
public class NumberTest
{

    /// 

    /// 
    /// 
    [TestMethod]
    public void Convert_To_Decimal_Test ( )
    {
        string v1 = "123.4";
        string v2 = "123,4";
        string v3 = "1,234.5";
        string v4 = "1.234,5";
        string v5 = "123";
        string v6 = "1,234,567.89";
        string v7 = "1.234.567,89";

        decimal a1 = v1.ToDecimal ( );
        decimal a2 = v2.ToDecimal ( );
        decimal a3 = v3.ToDecimal ( );
        decimal a4 = v4.ToDecimal ( );
        decimal a5 = v5.ToDecimal ( );
        decimal a6 = v6.ToDecimal ( );
        decimal a7 = v7.ToDecimal ( );

        Assert.AreEqual ( ( decimal ) 123.4, a1 );
        Assert.AreEqual ( ( decimal ) 123.4, a2 );
        Assert.AreEqual ( ( decimal ) 1234.5, a3 );
        Assert.AreEqual ( ( decimal ) 1234.5, a4 );
        Assert.AreEqual ( ( decimal ) 123, a5 );
        Assert.AreEqual ( ( decimal ) 1234567.89, a6 );
        Assert.AreEqual ( ( decimal ) 1234567.89, a7 );
    }
    /// 

    /// 
    /// 
    [TestMethod]
    public void Swap_Char_Test ( )
    {
        string v6 = "1,234,567.89";
        string v7 = "1.234.567,89";

        string a1 = v6.SwapChar ( ',', '.' );
        string a2 = v7.SwapChar ( ',', '.' );

        Assert.AreEqual ( "1.234.567,89", a1 );
        Assert.AreEqual ( "1,234,567.89", a2 );
    }
}