在C＃中将键盘语言从英语更改为其他语言时，如何以编程方式比较零

Question

I want to compare zero that is coming from TextBox as string for removing it from front in c#.

 private string RemoveLeadingZeros(string str)//TextBox.Text
        {
            int index = -1;
            for (int i = 0; i < str.Trim().Length; i++)
            {
                if (str[i] == '0')//This comparison fails if i change the keyboard language from english to some other language ex. chinese
                    continue;
                else
                {
                    index = i;
                    break;
                }
            }

            return (index != -1) ? str.Substring(index) : "0";
        }

So, for example if the string is "0001" it should return 1. This method fails if we change the keyboard language other than English (Example:chinese).

How can we compare the zero irrespective of the language changed from keyboard from English to some other language?

Answer 1

I checked a font containing CJK characters (Microsoft JhengHei on Windows 10), and inferred from it that a Chinese keyboard layout would return full-width numbers (starting at U+FF10). As other keyboard layouts may provide even different numbers, it would appear that the best choice is to use the char.GetNumericValue() method (see also What's the deal with char.GetNumericValue? ).

EDIT: Substring() with a single parameter returns the same string if the index is 0. Added trimming as in the original post, changed the method name to reflect it, and made it an extension method.

With that, your method would look as follows:

private static string TrimAndRemoveLeadingZeros(this string str)
{
    int idx = 0;
    if (string.IsNullOrEmpty(str)) return str;
    str = str.Trim();
    for (int i = 0; i < str.Length; i++)
    {
        int num = (int)char.GetNumericValue(str[i]);
        if (num == 0) idx++;
        else break;
    }
    return str.Substring(idx);
}