判断一个string是否可以为数字

方案一：Try...Catch(执行效率不高)//////名称：IsNumberic///功能

方案一：Try...Catch(执行效率不高) /// <summary> /// 名称：IsNumberic /// 功能：判断输入的是否是数字 /// 参数：string oText：源文本 /// 返回值：　bool true:是　false:否 /// </summary> /// <param name="oText"></param> /// <returns></returns> private bool IsNumberic(string oText) { try          { int var1=Convert.ToInt32 (oText); return true;          } catch { return false; } }

方案二：正则表达式(推荐) a) using System; using System.Text.RegularExpressions;

public bool IsNumber(String strNumber) { Regex objNotNumberPattern=new Regex("[^0-9.-]"); Regex objTwoDotPattern=new Regex("[0-9]*[.][0-9]*[.][0-9]*"); Regex objTwoMinusPattern=new Regex("[0-9]*[-][0-9]*[-][0-9]*"); String strValidRealPattern="^([-]|[.]|[-.]|[0-9])[0-9]*[.]*[0-9] $"; String strValidIntegerPattern="^([-]|[0-9])[0-9]*$"; Regex objNumberPattern =new Regex("(" strValidRealPattern ")|(" strValidIntegerPattern ")");

return !objNotNumberPattern.IsMatch(strNumber) && !objTwoDotPattern.IsMatch(strNumber) && !objTwoMinusPattern.IsMatch(strNumber) && objNumberPattern.IsMatch(strNumber); }

b) public static bool IsNumeric(string value) { return Regex.IsMatch(value, @"^[ -]?/d*[.]?/d*$"); } public static bool IsInt(string value) { return Regex.IsMatch(value, @"^[ -]?/d*$"); } public static bool IsUnsign(string value) { return Regex.IsMatch(value, @"^/d*[.]?/d*$"); } 方案三：遍历 a) public bool isnumeric(string str) {     char[] ch=new char[str.Length];     ch=str.ToCharArray();     for(int i=0;i<ch.Length;i )     {         if(ch[i]<48 || ch[i]>57)             return false;     }     return true; }

b) public bool IsInteger(string strIn) { bool bolResult=true; if(strIn=="") { bolResult=false; } else { foreach(char Char in strIn) { if(char.IsNumber(Char)) continue; else { bolResult=false; break; } } } return bolResult; }

c) public static bool isNumeric(string inString) { inString=inString.Trim(); bool haveNumber=false; bool haveDot=false; for(int i=0;i<inString.Length;i ) { if (Char.IsNumber(inString[i])) { haveNumber=true; } else if(inString[i]=='.') { if (haveDot) { return false; } else { haveDot=true; } } else if(i==0) { if(inString[i]!=' '&&inString[i]!='-') { return false; } } else { return false; } if(i>20) { return false; } } return haveNumber; } }

方案四：改写vb的IsNumeric源代码(执行效率不高)

//主调函数 public static bool IsNumeric(object Expression) {       bool flag1;       IConvertible convertible1 = null;       if (Expression is IConvertible)       {             convertible1 = (IConvertible) Expression;       }       if (convertible1 == null)       {             if (Expression is char[])             {                   Expression = new string((char[]) Expression);             }             else             {                   return false;             }       }       TypeCode code1 = convertible1.GetTypeCode();       if ((code1 != TypeCode.String) && (code1 != TypeCode.Char))       {             return Utils.IsNumericTypeCode(code1);       }       string text1 = convertible1.ToString(null);       try       {             long num2;             if (!StringType.IsHexOrOctValue(text1, ref num2))             {                   double num1;                   return DoubleType.TryParse(text1, ref num1);             }             flag1 = true;       }       catch (Exception)       {             flag1 = false;       }       return flag1; }

//子函数 // return Utils.IsNumericTypeCode(code1); internal static bool IsNumericTypeCode(TypeCode TypCode) {       switch (TypCode)       {             case TypeCode.Boolean:             case TypeCode.Byte:             case TypeCode.Int16:             case TypeCode.Int32:             case TypeCode.Int64:             case TypeCode.Single:             case TypeCode.Double:             case TypeCode.Decimal:             {                   return true;             }             case TypeCode.Char:             case TypeCode.SByte:             case TypeCode.UInt16:             case TypeCode.UInt32:             case TypeCode.UInt64:             {                   break;             }       }       return false; }

//----------------- //StringType.IsHexOrOctValue(text1, ref num2)) internal static bool IsHexOrOctValue(string Value, ref long i64Value) {       int num1;       int num2 = Value.Length;       while (num1 < num2)       {             char ch1 = Value[num1];             if (ch1 == '&')             {                   ch1 = char.ToLower(Value[num1 1], CultureInfo.InvariantCulture);                   string text1 = StringType.ToHalfwidthNumbers(Value.Substring(num1 2));                   if (ch1 == 'h')                   {                         i64Value = Convert.ToInt64(text1, 0x10);                   }                   else if (ch1 == 'o')                   {                         i64Value = Convert.ToInt64(text1, 8);                   }                   else                   {                         throw new FormatException();                   }                   return true;             }             if ((ch1 != ' ') && (ch1 != '/u3000'))             {                   return false;             }             num1 ;       }       return false; } //---------------------------------------------------- // DoubleType.TryParse(text1, ref num1); internal static bool TryParse(string Value, ref double Result) {       bool flag1;       CultureInfo info1 = Utils.GetCultureInfo();       NumberFormatInfo info3 = info1.NumberFormat;       NumberFormatInfo info2 = DecimalType.GetNormalizedNumberFormat(info3);       Value = StringType.ToHalfwidthNumbers(Value, info1);       if (info3 == info2)       {             return double.TryParse(Value, NumberStyles.Any, info2, out Result);       }       try       {             Result = double.Parse(Value, NumberStyles.Any, info2);             flag1 = true;       }       catch (FormatException)       {             flag1 = double.TryParse(Value, NumberStyles.Any, info3, out Result);       }       catch (Exception)       {             flag1 = false;       }       return flag1; }

方案五： 直接引用vb运行库(执行效率不高)

方法： 首先需要添加Visualbasic.runtime的引用  代码中Using Microsoft.visualbasic;  程序中用Information.isnumeric("ddddd");

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