C#判断一个string是否为数字 --zt

http://www.cnblogs.com/zm235/archive/2006/09/23/512742.html
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"); 

 
posted @ 2007-03-26 09:09  Nina  阅读(514)  评论(1编辑  收藏  举报