使用正则表达式…

Regex re = new Regex(@"\d+");
Match m = re.Match("test 66");

if (m.Success)
{
    Console.WriteLine(string.Format("RegEx found " + m.Value + " at position " + m.Index.ToString()));
}
else
{
    Console.WriteLine("You didn't enter a string containing a number!");
}

以下是我如何清理电话号码，让它只有数字:

string numericPhone = new String(phone.Where(Char.IsDigit).ToArray());

var match=Regex.Match(@"a99b",@"\d+");
if(match.Success)
{
    int val;
    if(int.TryParse(match.Value,out val))
    {
        //val is set
    }
}

我用什么来得到电话号码没有任何标点符号…

var phone = "(787) 763-6511";

string.Join("", phone.ToCharArray().Where(Char.IsDigit));

// result: 7877636511

var outputString = String.Join("", inputString.Where(Char.IsDigit));

获取字符串中的所有数字。 所以如果你用“1 + 2”这个例子，它会得到“12”。

基于上一个示例，我创建了一个方法:

private string GetNumberFromString(string sLongString, int iLimitNumbers)
{
    string sReturn = "NA";
    int iNumbersCounter = 0;
    int iCharCounter = 0; 

    string sAlphaChars = string.Empty;
    string sNumbers = string.Empty;
    foreach (char str in sLongString)
    {
        if (char.IsDigit(str))
        {
            sNumbers += str.ToString();
            iNumbersCounter++;
            if (iNumbersCounter == iLimitNumbers)
            {
                return sReturn = sNumbers;
            }
        }
        else
        {
            sAlphaChars += str.ToString();
            iCharCounter++;
            // reset the counter 
            iNumbersCounter = 0; 
        }
    }
    return sReturn;
}