How do I identify if a string is a number?

 

If I have these strings:

  • "abc" = false

  • "123" = true

  • "ab2" = false

    • Is there a command, like IsNumeric or something else, that can identify if a string is a valid number? 

    int n;
bool isNumeric = int.TryParse("123", out n);

    Update As of C# 7: 

    var isNumeric = int.TryParse("123", out int n);

    The var s can be replaced by their respective types!

    This will return true if input is all numbers. Don't know if it's any better than TryParse , but it will work. 

    Regex.IsMatch(input, @"^d+$")

    If you just want to know if it has one or more numbers mixed in with characters, leave off the ^ + and $ . 

    Regex.IsMatch(input, @"d")

    Edit: Actually I think it is better than TryParse because a very long string could potentially overflow TryParse.

    I've used this function several times: 

    public static bool IsNumeric(object Expression)
{
    double retNum;

    bool isNum = Double.TryParse(Convert.ToString(Expression), System.Globalization.NumberStyles.Any, System.Globalization.NumberFormatInfo.InvariantInfo, out retNum);
    return isNum;
}

    But you can also use; 

    bool b1 = Microsoft.VisualBasic.Information.IsNumeric("1"); //true
bool b2 = Microsoft.VisualBasic.Information.IsNumeric("1aa"); // false

    From Benchmarking IsNumeric Options

    alt text http://aspalliance.com/images/articleimages/80/Figure1.gif

    alt text http://aspalliance.com/images/articleimages/80/Figure2.gif

    链接地址: http://www.djcxy.com/p/64110.html

    上一篇: 我可以用番石榴包装文字到一个给定的宽度吗？

    下一篇: 如何识别字符串是否是数字？