string.Format("{0:G29}", decimal.Parse("2.00"))

string.Format("{0:G29}", decimal.Parse(Your_Variable))

像这样试试

string s = "2.4200";

s = s.TrimStart("0").TrimEnd("0", ".");

然后把它转换成浮点数

一个非常低级的方法，但我相信这将是最高效的方法，只使用快速整数计算(没有缓慢的字符串解析和区域性敏感的方法):

public static decimal Normalize(this decimal d)
{
    int[] bits = decimal.GetBits(d);

    int sign = bits[3] & (1 << 31);
    int exp = (bits[3] >> 16) & 0x1f;

    uint a = (uint)bits[2]; // Top bits
    uint b = (uint)bits[1]; // Middle bits
    uint c = (uint)bits[0]; // Bottom bits

    while (exp > 0 && ((a % 5) * 6 + (b % 5) * 6 + c) % 10 == 0)
    {
        uint r;
        a = DivideBy10((uint)0, a, out r);
        b = DivideBy10(r, b, out r);
        c = DivideBy10(r, c, out r);
        exp--;
    }

    bits[0] = (int)c;
    bits[1] = (int)b;
    bits[2] = (int)a;
    bits[3] = (exp << 16) | sign;
    return new decimal(bits);
}

private static uint DivideBy10(uint highBits, uint lowBits, out uint remainder)
{
    ulong total = highBits;
    total <<= 32;
    total = total | (ulong)lowBits;

    remainder = (uint)(total % 10L);
    return (uint)(total / 10L);
}

这很简单。

decimal decNumber = Convert.ToDecimal(value);
        return decNumber.ToString("0.####");

测试。

欢呼:)

试试下面的代码:

string value = "100";
value = value.Contains(".") ? value.TrimStart('0').TrimEnd('0').TrimEnd('.') : value.TrimStart('0');

在我看来，使用自定义数字格式字符串更安全。

decimal d = 0.00000000000010000000000m;
string custom = d.ToString("0.#########################");
// gives: 0,0000000000001
string general = d.ToString("G29");
// gives: 1E-13