C#判断一个string是否为数字

案一：Try...Catch(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)
using System.Text.RegularExpressions;
a)
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*$");
}

 public static bool isTel(string strInput)
{
        return Regex.IsMatch(strInput, @"\d{3}-\d{8}|\d{4}-\d{7}");
}

b)

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);
}

 


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;
       }