请问如何判断一个变量是数值型?

[QmStar]

在VB中用IsNumeric()就可以了,在C#中有没有对应的方法?

[marvelstack]

最简单使用try catch

专业一点使用正则表达式。

[AllenTing]

http://www.pconline.com.cn/pcedu/empolder/net/cs/0501/539898.html

[sskset]

public static bool IsNumber(string strCheck)
{
char[] charChecks = strCheck.ToCharArray();
foreach (char charCheck in charChecks)
{
//半角数字判断
if (!(((short)charCheck > 47) && ((short)charCheck < 58)))
{
return false;
}
}

return true;
}

[darksinada]

int i = 1234;
string i_Type = i.GetType().ToString();

long ii = 1234;
string ii_Type = ii.GetType().ToString();

float iii = 1234;
string iii_Type = iii.GetType().ToString();

-----------------------------

得到的i_Type = "System.Int32";ii_Type = "System.Int64";iii_Type = "System.Single".

其他的字符串处理楼主自己看着办吧？

[flyskywlh]

intvalue.GetType().ToString();

is your type

[kv4000]

刚才学到!

[CSDNATM]

判断一个string是否可以为数字


方案一：Try...Catch(执行效率不高)
/// <summary>
/// 名称：IsNumberic
/// 功能：判断输入的是否是数字
/// 参数：string oText：源文本
/// 返回值：　bool true:是　false:否
/// </summary>
/// <param name="oText"></param>
/// <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<ch.Length;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<inString.Length;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;
}

[CSDNATM]

函数：
public bool IsNumber(string number)
{
return Regex.IsMatch(number, @"^[+|-]?(\d+(\.\d*)?|\d{1,2}(,\d{3})*(\.\d*)?)$");
}

调用：
bool aa = IsNumber(this.textBox1.Text.Trim());

if(aa==true)
{
MessageBox.Show("数字？OK");
}
else
{
MessageBox.Show("数字？No");
}

[copage]

char.IsNumerica(s) s为string一般就可以了吧？

[flcandclf]

一个小问题，弄这么长的代码会看死人的

[QmStar]

谢谢大家了！！！