子串直到找到数字

Question

I have a string LCD32W58 . In this string I want substring until I get number
eg LCD32W58 --> LCD

If the string contains numeric at beginning then I want numbers until character start
eg 55LM9600 --? 55 55LM9600 --? 55

Answer 1

you can use something like this

if @nString like '[0-9]%'
    select @Result = left(@nString, patindex('%[A-Za-z]%', @nString) - 1)
else if @nString like '[A-Za-z]%'
    select @Result = left(@nString, patindex('%[0-9]%', @nString) - 1)

you can also use numbers and not numbers style

if @nString like '[0-9]%'
    select @Result = left(@nString, patindex('%[^0-9]%', @nString) - 1)
else
    select @Result = left(@nString, patindex('%[0-9]%', @nString) - 1)

Answer 2

The methode wroks only if you have just numbers and letters in your string

private string ParseString(string s)
{            
    int i = 0;
    int j = 0;
    foreach (char c in s)
    {            
        if (isAlphanummeric(c)
        {
            if (j > 0)
                break;
            i++;
        }
        else if(isNummeric(c)
        {
            if (i > 0)
                break;
            j++;
        }
        else
        {
            throw new NotSupportedException(
                      "Only letters and numbers are expected.");
        }
    }

    return (s.Substring(0, (i > 0 ? i: j)));
}

private bool isAlphanummeric(Char decValue)
{
   return ((decValue > 64) && (decValue < 91)) ||
          ((decValue > 98) && (decValue < 123));
}

private bool isNummeric(Char decValue)
{
   return ((decValue > 47) && (decValue < 58));
}