将字符串转换为十进制分隔符“.”和“,”的最佳方法是什么?

你有以下可能:

1. 1. 使用安装了计算机的当前区域性设置
   2. 您让用户决定在程序中设置其区域性->用户设置
2. 你不懂文化
   
   1. 你必须决定:你必须定义和记录你的决定

您可以创建一个临时 CultureInfo 分析时要使用的对象。

// get a temporary culture (clone) to modify
var ci = CultureInfo.InvariantCulture.Clone() as CultureInfo;
ci.NumberFormat.NumberDecimalSeparator = ",";
decimal number = decimal.Parse("1,1", ci); // 1.1

所以如果你不知道目标系统的文化,你也不知道你会得到什么样的价值,比如12.33或者12,33,你可以这样做

string amount = "12.33";
// or i.e. string amount = "12,33";

var c = System.Threading.Thread.CurrentThread.CurrentCulture;
var s = c.NumberFormat.CurrencyDecimalSeparator;

amount = amount.Replace(",", s);
amount = amount.Replace(".", s);

decimal transactionAmount = Convert.ToDecimal(amount); 

Parse ,就像这样:

string s = "11,20";

decimal c1 = decimal.Parse(s, new CultureInfo("fr-FR"));
decimal c2 = decimal.Parse(s, new CultureInfo("en-AU"));

Console.WriteLine(c1);
Console.WriteLine(c2);

下面是我的实现,有什么好主意吗?

/// <summary>
/// 
/// </summary>
public static class NumberExtensions
{
    /// <summary>
    /// Convert string value to decimal ignore the culture.
    /// </summary>
    /// <param name="value">The value.</param>
    /// <returns>Decimal value.</returns>
    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;
    }
    /// <summary>
    /// Swaps the char.
    /// </summary>
    /// <param name="value">The value.</param>
    /// <param name="from">From.</param>
    /// <param name="to">To.</param>
    /// <returns></returns>
    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
{

    /// <summary>
    /// 
    /// </summary>
    [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 );
    }
    /// <summary>
    /// 
    /// </summary>
    [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 );
    }
}

很好,仍然不是100%正确。

            case 1:
                var firstPunctuation = linq.ElementAt(0);
                var firstPunctuationOccurence = value.Where(x => x == firstPunctuation).Count();

                if (firstPunctuationOccurence == 1)
                {
                    // we assume it's a decimal separator (and not a group separator)
                    value = value.Replace(firstPunctuation.ToString(), format.NumberDecimalSeparator);
                }
                else
                {
                    // multiple occurence means that symbol is a group separator
                    value = value.Replace(firstPunctuation.ToString(), format.NumberGroupSeparator);
                }

                break;

使用胰蛋白酶两次,两种风格代表两种可能性
如果只有一个返回值,则使用该值 如果两者都返回一个值,则使用绝对值中较小的值。

如果使用错误的样式,对于同时使用分组和小数分隔符的数字,TryParse将返回0,但是如果字符串中没有分组分隔符(例如,数字小于1000),则在这两种情况下都将返回值,但“错误”的数字将更大(同样是绝对值)