current situation and issue

I currently have an issue to display the available amount of a crypto currency in my wallet in a meaningful way. the issue is that the usd equivalents of the cryptos are differing immensly and thus the required precisions are varying a lot.

For instance, lets say I have 50 USD worth in any given cryptocurrency of my wallet. At the time of writing, this would look like the following:

in a real world example, it looks like the following:

existing solution (for classic currencies)

Lets say I go for a classic formatting of currencies:

currency.ToString("0.##");

while this would work great for currencies such as shib or usdt, currencies with higher value such as btc or eth will have problems with this:

pseudo-code/solution

I think it would be feasible to go with 3 digits of precision for the first significant digit after the comma:

if (amount >= 1)
{ // in a range to show 2 decimals
    string result = amount.ToString("0.##"); // eg 5.93
}
else
{ // truncate to precision of 3
    // 0.0184432468325 -> "0.0184"
    // 0.00237392482309 -> "0.00237"
    // 0.00043930984274 -> "0.000439"
    // 0.00000000001279 -> "0.0000000000127"
    // 0.123000004234 -> "0.123"
}

how would I go about the last part (if amount is smaller 0)?

CodePudding user response：

Unsure this is a good approach or not, you may look for regex.

Regex 101 with Sample Test Data

^(0.0*\d{1,3})

The above regex captures the group amount with a pattern starting with "0.", has zero or more "0" and lastly any numeric characters with at least 1 and up to 3 occurrences.

public static string TruncateSmallerZeroCryptoAmt(double amount)
{
    Regex regex = new Regex("^(0.0*\\d{3})");
    var match = regex.Match(String.Format("{0:F20}", amount));
        
    return match.Value.TrimEnd('0');
}

The reason why is to convert double to string with a formatting pattern so that the output string will not have E (exponential).

While .TrimEnd('0') is to remove the extra zeros at the back due to previous formatting.

For example:

0.300 --> Display as 0.3

Sample .NET Fiddle