[总结]C#判断一个string是否可以为数字,五种解决方案!

判断一个string是否可以为数字

方案一：Try...Catch(执行效率不高)
///

1<summary>   
2/// 名称：IsNumberic   
3/// 功能：判断输入的是否是数字   
4/// 参数：string oText：源文本   
5/// 返回值： bool true:是 false:否   
6/// </summary>

///

1<param name="oText"/>

///

1<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

  1<ch.length;i++) ch[i]="" if(ch[i]<48="" {="" ||="">57)   
  2return false;   
  3}   
  4return true;   
  5} 
  6
  7b)   
  8public bool IsInteger(string strIn) {   
  9bool bolResult=true;   
 10if(strIn=="") {   
 11bolResult=false;   
 12}   
 13else {   
 14foreach(char Char in strIn) {   
 15if(char.IsNumber(Char))   
 16continue;   
 17else {   
 18bolResult=false;   
 19break;   
 20}   
 21}   
 22}   
 23return bolResult;   
 24} 
 25
 26c)   
 27public static bool isNumeric(string inString)   
 28{   
 29inString=inString.Trim();   
 30bool haveNumber=false;   
 31bool haveDot=false;   
 32for(int i=0;i<instring.length;i++) &&instring[i]!="-" (char.isnumber(instring[i]))="" (havedot)="" )="" else="" false;="" havedot="true;" havenumber="true;" if="" if(i="" if(instring[i]="." if(instring[i]!="+" return="" {="" }="">20)   
 33{   
 34return false;   
 35}   
 36}   
 37return haveNumber;   
 38}   
 39} 
 40
 41方案四：改写vb的IsNumeric源代码(执行效率不高) 
 42
 43//主调函数   
 44public static bool IsNumeric(object Expression)   
 45{   
 46bool flag1;   
 47IConvertible convertible1 = null;   
 48if (Expression is IConvertible)   
 49{   
 50convertible1 = (IConvertible) Expression;   
 51}   
 52if (convertible1 == null)   
 53{   
 54if (Expression is char[])   
 55{   
 56Expression = new string((char[]) Expression);   
 57}   
 58else   
 59{   
 60return false;   
 61}   
 62}   
 63TypeCode code1 = convertible1.GetTypeCode();   
 64if ((code1 != TypeCode.String) &amp;&amp; (code1 != TypeCode.Char))   
 65{   
 66return Utils.IsNumericTypeCode(code1);   
 67}   
 68string text1 = convertible1.ToString(null);   
 69try   
 70{   
 71long num2;   
 72if (!StringType.IsHexOrOctValue(text1, ref num2))   
 73{   
 74double num1;   
 75return DoubleType.TryParse(text1, ref num1);   
 76}   
 77flag1 = true;   
 78}   
 79catch (Exception)   
 80{   
 81flag1 = false;   
 82}   
 83return flag1;   
 84} 
 85
 86//子函数   
 87// return Utils.IsNumericTypeCode(code1);   
 88internal static bool IsNumericTypeCode(TypeCode TypCode)   
 89{   
 90switch (TypCode)   
 91{   
 92case TypeCode.Boolean:   
 93case TypeCode.Byte:   
 94case TypeCode.Int16:   
 95case TypeCode.Int32:   
 96case TypeCode.Int64:   
 97case TypeCode.Single:   
 98case TypeCode.Double:   
 99case TypeCode.Decimal:   
100{   
101return true;   
102}   
103case TypeCode.Char:   
104case TypeCode.SByte:   
105case TypeCode.UInt16:   
106case TypeCode.UInt32:   
107case TypeCode.UInt64:   
108{   
109break;   
110}   
111}   
112return false;   
113}   
114
115
116//-----------------   
117//StringType.IsHexOrOctValue(text1, ref num2))   
118internal static bool IsHexOrOctValue(string Value, ref long i64Value)   
119{   
120int num1;   
121int num2 = Value.Length;   
122while (num1 &lt; num2)   
123{   
124char ch1 = Value[num1];   
125if (ch1 == '&amp;')   
126{   
127ch1 = char.ToLower(Value[num1 + 1], CultureInfo.InvariantCulture);   
128string text1 = StringType.ToHalfwidthNumbers(Value.Substring(num1 + 2));   
129if (ch1 == 'h')   
130{   
131i64Value = Convert.ToInt64(text1, 0x10);   
132}   
133else if (ch1 == 'o')   
134{   
135i64Value = Convert.ToInt64(text1, 8);   
136}   
137else   
138{   
139throw new FormatException();   
140}   
141return true;   
142}   
143if ((ch1 != ' ') &amp;&amp; (ch1 != '\u3000'))   
144{   
145return false;   
146}   
147num1++;   
148}   
149return false;   
150}   
151//----------------------------------------------------   
152// DoubleType.TryParse(text1, ref num1);   
153internal static bool TryParse(string Value, ref double Result)   
154{   
155bool flag1;   
156CultureInfo info1 = Utils.GetCultureInfo();   
157NumberFormatInfo info3 = info1.NumberFormat;   
158NumberFormatInfo info2 = DecimalType.GetNormalizedNumberFormat(info3);   
159Value = StringType.ToHalfwidthNumbers(Value, info1);   
160if (info3 == info2)   
161{   
162return double.TryParse(Value, NumberStyles.Any, info2, out Result);   
163}   
164try   
165{   
166Result = double.Parse(Value, NumberStyles.Any, info2);   
167flag1 = true;   
168}   
169catch (FormatException)   
170{   
171flag1 = double.TryParse(Value, NumberStyles.Any, info3, out Result);   
172}   
173catch (Exception)   
174{   
175flag1 = false;   
176}   
177return flag1;   
178} 
179
180方案五： 直接引用vb运行库(执行效率不高) 
181
182方法： 首先需要添加Visualbasic.runtime的引用   
183代码中Using Microsoft.visualbasic;   
184程序中用Information.isnumeric("ddddd");</instring.length;i++)></ch.length;i++)>