C # Determines if a string is a numeric string

In C # programming, sometimes we need to determine whether a string is a numeric string, and we can do it in the following two ways.
" Method One ": Use the try{} catch{} statement.
We can attempt to convert a string variable of type string to an int type in a try statement block, and if the string is not a numeric string, an exception is thrown, in which case the exception can be caught in the catch statement block. Once an exception is found, it is not a numeric string.
We can convert a string type to an int type in three ways.
(1) Int. Parse (string);
(2) convert.toint16 (string); When the number of digits in the string is greater than 4 , use Convert.ToInt32 ()
(3) Convert.ToInt32 (string);

Add a text box TextBox1, and a button Button1, when the button is clicked, determines whether the content in the text box is a numeric string, and then outputs the converted value.

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protected void Button1_Click(object sender, EventArgs e){        string message = TextBox1.Text.Trim();        int result;        if(isNumberic(message,out result))        {            string tt="<script>alert(‘匹配成功，转换后的整数为"+result+"‘)</script>";            Page.ClientScript.RegisterStartupScript(this.GetType(), "", tt);        }        else            Page.ClientScript.RegisterStartupScript(this.GetType(), "", "<script>alert(‘匹配失败！‘)</script>");}protected bool isNumberic(string message,out int result){       //判断是否为整数字符串       //是的话则将其转换为数字并将其设为out类型的输出值、返回true, 否则为false        result = -1;   //result 定义为out 用来输出值        try        {          //当数字字符串的为是少于4时，以下三种都可以转换，任选一种          //如果位数超过4的话，请选用Convert.ToInt32() 和int.Parse()           //result = int.Parse(message);          //result = Convert.ToInt16(message);            result = Convert.ToInt32(message);                return true;        }        catch        {            return false;        }}

The above method can change int to double, such as double. Parse () so that you can determine whether a floating-point string
" method Two ": Judging by regular Expressions .
Use regular expressions to verify that the string is a numeric string. We're going to use the IsMatch () method of the Regex class. This class is in System.Text.RegularExpressions; You can pass the using System.Text.RegularExpressions; Import namespaces to access the Regex class. It can also be accessed directly through System.Text.RegularExpressions.Regex .

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protected bool isNumberic(string message,out int result){        System.Text.RegularExpressions.Regex rex=        new System.Text.RegularExpressions.Regex(@"^\d+$");        result = -1;        if (rex.IsMatch(message))        {            result = int.Parse(message);            return true;        }        else            return false;}

The regular expression to determine whether the match, not only can be used to make a simple judgment match, but also can be accurate matching, such as the judge whether it is a six-bit numeric string, email matching and so on. Regular expressions are a good way to do this.

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protected void Button1_Click(object sender, EventArgs e){        string message = TextBox1.Text.Trim();        isNumeric(message); //判断字符串是否为5为整数字符串}protected void isNumeric(string message){       if (message != "" && Regex.IsMatch(message, @"^\d{5}$"))       {          //成功          Page.ClientScript.RegisterStartupScript(this.GetType(), "", "<script>alert(‘匹配通过！确实是五位的整数字符串‘)</script>");       }       else           //失败           Page.ClientScript.RegisterStartupScript(this.GetType(), "", "<script>alert(‘匹配失败！‘)</script>");}

C # Determines if a string is a numeric string

C # Determines if a string is a numeric string