c#判断是否为整数或者数值

  有时需要判断输入的值，但又不想限制输入，因此多了检测的步骤。这里列举的是判断输入的内容是否是整数或者其它小数的数值.

  利用int类型自带的TryParse(string, ou int) 方法可以解决问题，此方法通过对应的输入内容string，如果是整数则返回int，不是则判断为false。具体代码如下：

String a = "123";
String b = "12.3";
String c = "abc";
String d = "厉害";
String e = "୧(๑•̀◡•́๑)૭";

int num = 0;
Console.WriteLine("a:" + a + " : " + int.TryParse(a, out num));
Console.WriteLine("b:" + b + " : " + int.TryParse(b, out num));
Console.WriteLine("c:" + c + " : " + int.TryParse(c, out num));
Console.WriteLine("d:" + d + " : " + int.TryParse(d, out num));
Console.WriteLine("e:" + e + " : " + int.TryParse(e, out num));

Console.ReadKey();

  运行结果如图所示：

  正则表达式的效果是杠杆的，这里只是判断是否是整数，这个用正则来实现是十分简单的。代码如图所示：

String a = "123";
String b = "12.3";
String c = "abc";
String d = "厉害";
String e = "୧(๑•̀◡•́๑)૭";

System.Text.RegularExpressions.Regex regex = new 
System.Text.RegularExpressions.Regex(@"^[0-9]d*$");

Console.WriteLine("a:" + a + " : " + regex.IsMatch(a));
Console.WriteLine("b:" + b + " : " + regex.IsMatch(b));
Console.WriteLine("c:" + c + " : " + regex.IsMatch(c));
Console.WriteLine("d:" + d + " : " + regex.IsMatch(d));
Console.WriteLine("e:" + e + " : " + regex.IsMatch(e));

Console.ReadKey();

  运行结果如图：

  与判断整数类似，这个也是可以有对应类型的判断和正则的判断，这里利用的是double或者decimal的值类型方法判断，效果还是很好的。对应代码如下：

String a = "123";
String b = "12.3";
String c = "abc";
String d = "厉害";
String e = "୧(๑•̀◡•́๑)૭";

decimal num = 0;
Console.WriteLine("a:" + a + " : " + decimal.TryParse(a, out num));
Console.WriteLine("b:" + b + " : " + decimal.TryParse(b, out num));
Console.WriteLine("c:" + c + " : " + decimal.TryParse(c, out num));
Console.WriteLine("d:" + d + " : " + decimal.TryParse(d, out num));
Console.WriteLine("e:" + e + " : " + decimal.TryParse(e, out num));

Console.ReadKey();

  运行结果如下：

  直接上代码：

String a = "123";
String b = "12.3";
String c = "abc";
String d = "厉害";
String e = "୧(๑•̀◡•́๑)૭";

System.Text.RegularExpressions.Regex regex = new 
System.Text.RegularExpressions.Regex(@"^-?d+$|^(-?d+)(.d+)?$");

Console.WriteLine("a:" + a + " : " + regex.IsMatch(a));
Console.WriteLine("b:" + b + " : " + regex.IsMatch(b));
Console.WriteLine("c:" + c + " : " + regex.IsMatch(c));
Console.WriteLine("d:" + d + " : " + regex.IsMatch(d));
Console.WriteLine("e:" + e + " : " + regex.IsMatch(e));

Console.ReadKey();

  运行结果如下：

  总体看来如果要判断输入的内容，正则表达才是万金油。