C#判断一个string是否可以为数字

方案一：TryCatch(执行效率不高)


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    

{


        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        

{


               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");