C#正则表达式应用范例

March 25,2004

The following example shows the use of Regular Expresssions in C#.This program has basic validation scripts for validation easily useable in all programs.

/*
<HowToCompile>
  csc /r:System.Text.RegularExpressions.dll,System.dll Validation.cs
</HowToComplie>
*/


using System.Text.RegularExpressions;
using System;

class Validation
{
  public static void Main()
  {
String strToTest;
Validation objValidate=new Validation();

Console.Write("Enter a String to Test for Alphabets:");
strToTest=Console.ReadLine();
if(objValidate.IsAlpha(strToTest))
{
   Console.WriteLine("{0} is Valid Alpha String",strToTest);
}
else
{
   Console.WriteLine("{0} is not a Valid Alpha String",strToTest);
}
  }

  // Function to test for Positive Integers.

  public bool IsNaturalNumber(String strNumber)
  {
Regex objNotNaturalPattern=new Regex("[^0-9]");
Regex objNaturalPattern=new Regex("0*[1-9][0-9]*");

return  !objNotNaturalPattern.IsMatch(strNumber) &&
         objNaturalPattern.IsMatch(strNumber);
  }

  // Function to test for Positive Integers with zero inclusive

public bool IsWholeNumber(String strNumber)
{
   Regex objNotWholePattern=new Regex("[^0-9]");

   return !objNotWholePattern.IsMatch(strNumber);
}

  // Function to Test for Integers both Positive & Negative

public bool IsInteger(String strNumber)
{
   Regex objNotIntPattern=new Regex("[^0-9-]");
   Regex objIntPattern=new Regex("^-[0-9]+$|^[0-9]+$");

   return  !objNotIntPattern.IsMatch(strNumber) &&
            objIntPattern.IsMatch(strNumber);
}

  // Function to Test for Positive Number both Integer & Real

  public bool IsPositiveNumber(String strNumber)
  {
Regex objNotPositivePattern=new Regex("[^0-9.]");
Regex objPositivePattern=new Regex("^[.][0-9]+$|[0-9]*[.]*[0-9]+$");
Regex objTwoDotPattern=new Regex("[0-9]*[.][0-9]*[.][0-9]*");

return !objNotPositivePattern.IsMatch(strNumber) &&
         objPositivePattern.IsMatch(strNumber)  &&
         !objTwoDotPattern.IsMatch(strNumber);
  }

  // Function to test whether the string is valid number or not
  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);
  }

  // Function To test for Alphabets.

  public bool IsAlpha(String strToCheck)
  {
Regex objAlphaPattern=new Regex("[^a-zA-Z]");

return !objAlphaPattern.IsMatch(strToCheck);
  }

  // Function to Check for AlphaNumeric.

  public bool IsAlphaNumeric(String strToCheck)
  {
Regex objAlphaNumericPattern=new Regex("[^a-zA-Z0-9]");

return !objAlphaNumericPattern.IsMatch(strToCheck);
  }

}

There is another simple way to perform these validation think of it while the next article comes.