Revised comparison relational operator articles

docs/csharp/language-reference/operators/equality-comparison-operator.md

@@ -19,6 +19,9 @@ Operands of the [built-in value types](../keywords/value-types-table.md) are equ
 
 [!code-csharp-interactive[value types equality](~/samples/snippets/csharp/language-reference/operators/EqualityAndNonEqualityExamples.cs#ValueTypesEquality)]
 
+> [!NOTE]
+> For relational operators `==`, `>`, `<`, `>=`, and `<=`, if any of the operands is not a number (<xref:System.Double.NaN?displayProperty=nameWithType> or <xref:System.Single.NaN?displayProperty=nameWithType>) the result of operation is `false`. That means that the `NaN` value is neither greater than, less than, nor equal to any other `double` (or `float`) value. For more information and examples, see the <xref:System.Double.NaN?displayProperty=nameWithType> or <xref:System.Single.NaN?displayProperty=nameWithType> reference article.
+
 Two operands of the same [enum](../keywords/enum.md) type are equal if the corresponding values of the underlying integral type are equal.
 
 By default, the `==` operator is not defined for a user-defined [struct](../keywords/struct.md) type. A user-defined type can [overload](#operator-overloadability) the `==` operator.

docs/csharp/language-reference/operators/greater-than-equal-operator.md

@@ -1,8 +1,7 @@
 ---
 title: ">= Operator - C# Reference"
 ms.custom: seodec18
-
-ms.date: 07/20/2015
+ms.date: 12/18/2018
 f1_keywords: 
   - ">=_CSharpKeyword"
 helpviewer_keywords: 
@@ -11,16 +10,29 @@ helpviewer_keywords:
 ms.assetid: 0db4dcaf-56a3-4884-a7ad-35f64978a58d
 ---
 # >= Operator (C# Reference)
-All numeric and enumeration types define a "greater than or equal" relational operator, `>=` that returns `true` if the first operand is greater than or equal to the second, `false` otherwise.  
-
-## Remarks  
- User-defined types can overload the `>=` operator. For more information, see [operator](../../../csharp/language-reference/keywords/operator.md). If `>=` is overloaded, [<=](../../../csharp/language-reference/operators/less-than-equal-operator.md) must also be overloaded. Operations on integral types are generally allowed on enumeration.  
-
-## Example  
- [!code-csharp[csRefOperators#39](../../../csharp/language-reference/operators/codesnippet/CSharp/greater-than-equal-operator_1.cs)]  
-
-## See Also
-
-- [C# Reference](../../../csharp/language-reference/index.md)  
-- [C# Programming Guide](../../../csharp/programming-guide/index.md)  
-- [C# Operators](../../../csharp/language-reference/operators/index.md)
+
+The "greater than or equal" relational operator `>=` returns `true` if its first operand is greater than or equal to its second operand, `false` otherwise. All numeric and  enumeration types support the `>=` operator. For operands of the same [enum](../keywords/enum.md) type, the corresponding values of the underlying integral type are compared.
+
+> [!NOTE]
+> For relational operators `==`, `>`, `<`, `>=`, and `<=`, if any of the operands is not a number (<xref:System.Double.NaN?displayProperty=nameWithType> or <xref:System.Single.NaN?displayProperty=nameWithType>) the result of operation is `false`. That means that the `NaN` value is neither greater than, less than, nor equal to any other `double` (or `float`) value. For more information and examples, see the <xref:System.Double.NaN?displayProperty=nameWithType> or <xref:System.Single.NaN?displayProperty=nameWithType> reference article.
+
+The following example demonstrates the usage of the `>=` operator:
+
+[!code-csharp-interactive[greater than or equal example](~/samples/snippets/csharp/language-reference/operators/GreaterAndLessOperatorsExamples.cs#GreaterOrEqual)]
+
+## Operator overloadability
+
+User-defined types can [overload](../keywords/operator.md) the `>=` operator. If a type overloads the "greater than or equal" operator `>=`, it must also overload the ["less than or equal" operator](less-than-equal-operator.md) `<=`.
+
+## C# language specification
+
+For more information, see the [Relational and type-testing operators](~/_csharplang/spec/expressions.md#relational-and-type-testing-operators) section of the [C# language specification](../language-specification/index.md).
+
+## See also
+
+- [C# Reference](../index.md)
+- [C# Programming Guide](../../programming-guide/index.md)
+- [C# Operators](index.md)
+- [> Operator](greater-than-operator.md)
+- [== Operator](equality-comparison-operator.md)
+- <xref:System.IComparable%601?displayProperty=nameWithType>

docs/csharp/language-reference/operators/greater-than-operator.md

@@ -1,8 +1,7 @@
 ---
 title: "> Operator - C# Reference"
 ms.custom: seodec18
-
-ms.date: 07/20/2015
+ms.date: 12/18/2018
 f1_keywords: 
   - ">_CSharpKeyword"
 helpviewer_keywords: 
@@ -11,17 +10,28 @@ helpviewer_keywords:
 ms.assetid: 26d3cb69-9c0b-4cc5-858b-5be1abd6659d
 ---
 # > Operator (C# Reference)
-All numeric and enumeration types define a "greater than" relational operator (`>`) that returns `true` if the first operand is greater than the second, `false` otherwise.  
-
-## Remarks  
- User-defined types can overload the `>` operator (see [operator](../../../csharp/language-reference/keywords/operator.md)). If `>` is overloaded, [<](../../../csharp/language-reference/operators/less-than-operator.md) must also be overloaded.
-
-## Example  
- [!code-csharp[csRefOperators#29](../../../csharp/language-reference/operators/codesnippet/CSharp/greater-than-operator_1.cs)]  
-
-## See Also
-
-- [C# Reference](../../../csharp/language-reference/index.md)  
-- [C# Programming Guide](../../../csharp/programming-guide/index.md)  
-- [C# Operators](../../../csharp/language-reference/operators/index.md)  
-- [explicit](../../../csharp/language-reference/keywords/explicit.md)
+
+The "greater than" relational operator `>` returns `true` if its first operand is greater than its second operand, `false` otherwise. All numeric and enumeration types support the `>` operator. For operands of the same [enum](../keywords/enum.md) type, the corresponding values of the underlying integral type are compared.
+
+> [!NOTE]
+> For relational operators `==`, `>`, `<`, `>=`, and `<=`, if any of the operands is not a number (<xref:System.Double.NaN?displayProperty=nameWithType> or <xref:System.Single.NaN?displayProperty=nameWithType>) the result of operation is `false`. That means that the `NaN` value is neither greater than, less than, nor equal to any other `double` (or `float`) value. For more information and examples, see the <xref:System.Double.NaN?displayProperty=nameWithType> or <xref:System.Single.NaN?displayProperty=nameWithType> reference article.
+
+The following example demonstrates the usage of the `>` operator:
+
+[!code-csharp-interactive[greater than example](~/samples/snippets/csharp/language-reference/operators/GreaterAndLessOperatorsExamples.cs#Greater)]
+
+## Operator overloadability
+
+User-defined types can [overload](../keywords/operator.md) the `>` operator. If a type overloads the "greater than" operator `>`, it must also overload the ["less than" operator](less-than-operator.md) `<`.
+
+## C# language specification
+
+For more information, see the [Relational and type-testing operators](~/_csharplang/spec/expressions.md#relational-and-type-testing-operators) section of the [C# language specification](../language-specification/index.md).
+
+## See also
+
+- [C# Reference](../index.md)
+- [C# Programming Guide](../../programming-guide/index.md)
+- [C# Operators](index.md)
+- [>= Operator](greater-than-equal-operator.md)
+- <xref:System.IComparable%601?displayProperty=nameWithType>

docs/csharp/language-reference/operators/less-than-equal-operator.md

@@ -1,8 +1,7 @@
 ---
 title: "<= Operator - C# Reference"
 ms.custom: seodec18
-
-ms.date: 07/20/2015
+ms.date: 12/18/2018
 f1_keywords: 
   - "<=_CSharpKeyword"
 helpviewer_keywords: 
@@ -11,17 +10,29 @@ helpviewer_keywords:
 ms.assetid: bb0caec9-d253-4105-b8bc-5252233251e4
 ---
 # &lt;= Operator (C# Reference)
-All numeric and enumeration types define a "less than or equal" relational operator (`<=`) that returns `true` if the first operand is less than or equal to the second, `false` otherwise.  
-
-## Remarks  
- User-defined types can overload the `<=` operator. For more information, see [operator](../../../csharp/language-reference/keywords/operator.md). If `<=` is overloaded, [>=](../../../csharp/language-reference/operators/greater-than-equal-operator.md) must also be overloaded. Operations on integral types are generally allowed on enumeration.  
-
-## Example  
- [!code-csharp[csRefOperators#32](../../../csharp/language-reference/operators/codesnippet/CSharp/less-than-equal-operator_1.cs)]  
-
-## See Also
-
-- [C# Reference](../../../csharp/language-reference/index.md)  
-- [C# Programming Guide](../../../csharp/programming-guide/index.md)  
-- [C# Operators](../../../csharp/language-reference/operators/index.md)  
-- [explicit](../../../csharp/language-reference/keywords/explicit.md)
+
+The "less than or equal" relational operator `<=` returns `true` if its first operand is less than or equal to its second operand, `false` otherwise. All numeric and enumeration types support the `<=` operator. For operands of the same [enum](../keywords/enum.md) type, the corresponding values of the underlying integral type are compared.
+
+> [!NOTE]
+> For relational operators `==`, `>`, `<`, `>=`, and `<=`, if any of the operands is not a number (<xref:System.Double.NaN?displayProperty=nameWithType> or <xref:System.Single.NaN?displayProperty=nameWithType>) the result of operation is `false`. That means that the `NaN` value is neither greater than, less than, nor equal to any other `double` (or `float`) value. For more information and examples, see the <xref:System.Double.NaN?displayProperty=nameWithType> or <xref:System.Single.NaN?displayProperty=nameWithType> reference article.
+
+The following example demonstrates the usage of the `<=` operator:
+
+[!code-csharp-interactive[less than or equal example](~/samples/snippets/csharp/language-reference/operators/GreaterAndLessOperatorsExamples.cs#LessOrEqual)]
+
+## Operator overloadability
+
+User-defined types can [overload](../keywords/operator.md) the `<=` operator. If a type overloads the "less than or equal" operator `<=`, it must also overload the ["greater than or equal" operator](greater-than-equal-operator.md) `>=`.
+
+## C# language specification
+
+For more information, see the [Relational and type-testing operators](~/_csharplang/spec/expressions.md#relational-and-type-testing-operators) section of the [C# language specification](../language-specification/index.md).
+
+## See also
+
+- [C# Reference](../index.md)
+- [C# Programming Guide](../../programming-guide/index.md)
+- [C# Operators](index.md)
+- [< Operator](less-than-operator.md)
+- [== Operator](equality-comparison-operator.md)
+- <xref:System.IComparable%601?displayProperty=nameWithType>

docs/csharp/language-reference/operators/less-than-operator.md

@@ -1,8 +1,7 @@
 ---
 title: "< Operator - C# Reference"
 ms.custom: seodec18
-
-ms.date: 07/20/2015
+ms.date: 12/18/2018
 f1_keywords: 
   - "<_CSharpKeyword"
 helpviewer_keywords: 
@@ -11,16 +10,28 @@ helpviewer_keywords:
 ms.assetid: 38cb91e6-79a6-48ec-9c1e-7b71fd8d2b41
 ---
 # &lt; Operator (C# Reference)
-All numeric and enumeration types define a "less than" relational operator (`<`) that returns `true` if the first operand is less than the second, `false` otherwise.  
-
-## Remarks  
- User-defined types can overload the `<` operator (see [operator](../../../csharp/language-reference/keywords/operator.md)). If `<` is overloaded, [>](../../../csharp/language-reference/operators/greater-than-operator.md) must also be overloaded.
-
-## Example  
- [!code-csharp[csRefOperators#24](../../../csharp/language-reference/operators/codesnippet/CSharp/less-than-operator_1.cs)]  
-
-## See Also
-
-- [C# Reference](../../../csharp/language-reference/index.md)  
-- [C# Programming Guide](../../../csharp/programming-guide/index.md)  
-- [C# Operators](../../../csharp/language-reference/operators/index.md)
+
+The "less than" relational operator `<` returns `true` if its first operand is less than its second operand, `false` otherwise. All numeric and enumeration types support the `<` operator. For operands of the same [enum](../keywords/enum.md) type, the corresponding values of the underlying integral type are compared.
+
+> [!NOTE]
+> For relational operators `==`, `>`, `<`, `>=`, and `<=`, if any of the operands is not a number (<xref:System.Double.NaN?displayProperty=nameWithType> or <xref:System.Single.NaN?displayProperty=nameWithType>) the result of operation is `false`. That means that the `NaN` value is neither greater than, less than, nor equal to any other `double` (or `float`) value. For more information and examples, see the <xref:System.Double.NaN?displayProperty=nameWithType> or <xref:System.Single.NaN?displayProperty=nameWithType> reference article.
+
+The following example demonstrates the usage of the `<` operator:
+
+[!code-csharp-interactive[less than example](~/samples/snippets/csharp/language-reference/operators/GreaterAndLessOperatorsExamples.cs#Less)]
+
+## Operator overloadability
+
+User-defined types can [overload](../keywords/operator.md) the `<` operator. If a type overloads the "less than" operator `<`, it must also overload the ["greater than" operator](greater-than-operator.md) `>`.
+
+## C# language specification
+
+For more information, see the [Relational and type-testing operators](~/_csharplang/spec/expressions.md#relational-and-type-testing-operators) section of the [C# language specification](../language-specification/index.md).
+
+## See also
+
+- [C# Reference](../index.md)
+- [C# Programming Guide](../../programming-guide/index.md)
+- [C# Operators](index.md)
+- [<= Operator](less-than-equal-operator.md)
+- <xref:System.IComparable%601?displayProperty=nameWithType>