Double.CompareTo方法用于将当前实例与指定对象或Double对象进行比较。它将返回一个整数，该整数显示当前实例的值是大于，小于还是等于指定对象或Double对象的值。此方法的重载列表中有2种方法，如下所示：
- CompareTo(Double)方法
- CompareTo(Object)方法
Double.CompareTo(Double)方法
Double.CompareTo()方法用于将当前实例与指定的双精度浮点数进行比较，并返回一个整数，该整数显示此实例的值是否小于，等于或大于指定的值。双精度浮点数。
句法：
public int CompareTo (double value);在这里，需要一个双精度浮点数进行比较。
返回值：该方法返回一个带符号的数字，指示此实例和value的相对值。
- 小于零：此实例小于value或此实例不是数字(NaN)且value是数字。
- 零：此实例等于value，或者此实例和value都不是数字(NaN)，PositiveInfinity或NegativeInfinity。
- 大于零：此实例大于值，或者此实例是数字，而值不是数字(NaN)。
下面的程序说明了Double.CompareTo(Double)方法的用法：
范例1：
// C# program to demonstrate the
// Double.CompareTo(Double)
// Method
using System;
using System.Globalization;
class GFG {
// Main Method
public static void Main()
{
// Declaring and initializing value1
double value1 = 10d;
// Declaring and initializing value2
double value2 = 20d;
// compare both double value
// using CompareTo() method
int status = value1.CompareTo(value2);
// checking the status
if (status > 0)
Console.WriteLine("{0} is greater than {1}",
value1, value2);
else if (status < 0)
Console.WriteLine("{0} is less than {1}",
value1, value2);
else
Console.WriteLine("{0} is equal to {1}",
value1, value2);
}
}
输出：
10 is less than 20
范例2：
// C# program to demonstrate the
// Double.CompareTo(Double)
// Method
using System;
using System.Globalization;
class GFG {
// Main Method
public static void Main()
{
// calling get() method
get(5d, 7d);
get(5.5d, 4.5d);
get(10d, 20d);
get(7.5d, 19.5d);
}
// defining get() method
public static void get(double value1,
double value2)
{
// compare both double value
// using CompareTo() method
int status = value1.CompareTo(value2);
// checking the status
if (status > 0)
Console.WriteLine("{0} is greater than {1}",
value1, value2);
else if (status < 0)
Console.WriteLine("{0} is less than {1}",
value1, value2);
else
Console.WriteLine("{0} is equal to {1}",
value1, value2);
}
}
输出：
5 is less than 7
5.5 is greater than 4.5
10 is less than 20
7.5 is less than 19.5
Double.CompareTo(Object)方法
Double.CompareTo()方法用于将当前实例与指定对象进行比较，并返回一个整数，该整数指示当前实例的值是否小于，等于或大于指定对象的值。
句法：
public int CompareTo (object value);在这里，它需要一个对象进行比较，或者为null。
返回值：该方法返回一个带符号的数字，指示此实例和value的相对值。
- 小于零：此实例小于value或此实例不是数字(NaN)且value是数字。
- 零：此实例等于value，或者此实例和value都不是数字(NaN)，PositiveInfinity或NegativeInfinity。
- 大于零：此实例大于value或此实例是一个数字，而值不是一个数字(NaN)。
异常：如果value不是Double，则抛出ArgumentException。
下面的程序说明Double.CompareTo(Object)方法的用法：
范例1：
// C# program to demonstrate the
// Double.CompareTo(object)
// Method
using System;
using System.Globalization;
class GFG {
// Main Method
public static void Main()
{
try {
// Declaring and initializing value1
double value1 = 10d;
// Declaring and initializing value2
object value2 = 20d;
// compare both double value
// using CompareTo() method
int status = value1.CompareTo(value2);
// checking the status
if (status > 0)
Console.WriteLine("{0} is greater than {1}",
value1, value2);
else if (status < 0)
Console.WriteLine("{0} is less than {1}",
value1, value2);
else
Console.WriteLine("{0} is equal to {1}",
value1, value2);
}
catch (ArgumentException e)
{
Console.WriteLine("value2 must be double");
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
}
}
输出：
10 is less than 20
示例2：对于ArgumentException
// C# program to demonstrate the
// Double.CompareTo(object)
// Method
using System;
using System.Globalization;
class GFG {
// Main Method
public static void Main()
{
try {
// Declaring and initializing value1
double value1 = 10d;
// Declaring and initializing value2
object value2 = 1 / 3;
// compare both double value
// using CompareTo() method
int status = value1.CompareTo(value2);
// checking the status
if (status > 0)
Console.WriteLine("{0} is greater than {1}",
value1, value2);
else if (status < 0)
Console.WriteLine("{0} is less than {1}",
value1, value2);
else
Console.WriteLine("{0} is equal to {1}",
value1, value2);
}
catch (ArgumentException e)
{
Console.WriteLine("value2 must be double");
Console.Write("Exception Thrown: ");
Console.Write("{0}", e.GetType(), e.Message);
}
}
}
输出：
value2 must be double
Exception Thrown: System.ArgumentException
参考：
- https://docs.microsoft.com/zh-cn/dotnet/api/system.double.compareto?view=netframework-4.7.2