C# reference: Consolidated articles about checked and unchecked statements (#30738)

* C# reference: Consolidated articles about checked and unchecked statements

* Additional edits

* Addressed feedback

* Addressed feedback

* Update docs/csharp/language-reference/statements/checked-and-unchecked.md

Co-authored-by: Bill Wagner <[email protected]>

Author: pkulikov

.openpublishing.redirection.csharp.json

@@ -455,6 +455,14 @@
             "source_path_from_root": "/docs/csharp/language-reference/keywords/char.md",
             "redirect_url": "/dotnet/csharp/language-reference/builtin-types/char"
         },
+        {
+            "source_path_from_root": "/docs/csharp/language-reference/keywords/checked.md",
+            "redirect_url": "/dotnet/csharp/language-reference/statements/checked-and-unchecked"
+        },
+        {
+            "source_path_from_root": "/docs/csharp/language-reference/keywords/checked-and-unchecked.md",
+            "redirect_url": "/dotnet/csharp/language-reference/statements/checked-and-unchecked"
+        },
         {
             "source_path_from_root": "/docs/csharp/language-reference/keywords/continue.md",
             "redirect_url": "/dotnet/csharp/language-reference/statements/jump-statements"
@@ -699,6 +707,10 @@
             "source_path_from_root": "/docs/csharp/language-reference/keywords/ulong.md",
             "redirect_url": "/dotnet/csharp/language-reference/builtin-types/integral-numeric-types"
         },
+        {
+            "source_path_from_root": "/docs/csharp/language-reference/keywords/unchecked.md",
+            "redirect_url": "/dotnet/csharp/language-reference/statements/checked-and-unchecked"
+        },
         {
             "source_path_from_root": "/docs/csharp/language-reference/keywords/ushort.md",
             "redirect_url": "/dotnet/csharp/language-reference/builtin-types/integral-numeric-types"

docs/csharp/language-reference/builtin-types/numeric-conversions.md

@@ -77,7 +77,7 @@ The following table shows the predefined explicit conversions between the built-
 
 Also note that:
 
-- When you convert a value of an integral type to another integral type, the result depends on the overflow [checking context](../keywords/checked-and-unchecked.md). In a checked context, the conversion succeeds if the source value is within the range of the destination type. Otherwise, an <xref:System.OverflowException> is thrown. In an unchecked context, the conversion always succeeds, and proceeds as follows:
+- When you convert a value of an integral type to another integral type, the result depends on the [overflow-checking context](../statements/checked-and-unchecked.md). In a checked context, the conversion succeeds if the source value is within the range of the destination type. Otherwise, an <xref:System.OverflowException> is thrown. In an unchecked context, the conversion always succeeds, and proceeds as follows:
 
   - If the source type is larger than the destination type, then the source value is truncated by discarding its "extra" most significant bits. The result is then treated as a value of the destination type.
 
@@ -87,7 +87,7 @@ Also note that:
 
 - When you convert a `decimal` value to an integral type, this value is rounded towards zero to the nearest integral value. If the resulting integral value is outside the range of the destination type, an <xref:System.OverflowException> is thrown.
 
-- When you convert a `double` or `float` value to an integral type, this value is rounded towards zero to the nearest integral value. If the resulting integral value is outside the range of the destination type, the result depends on the overflow [checking context](../keywords/checked-and-unchecked.md). In a checked context, an <xref:System.OverflowException> is thrown, while in an unchecked context, the result is an unspecified value of the destination type.
+- When you convert a `double` or `float` value to an integral type, this value is rounded towards zero to the nearest integral value. If the resulting integral value is outside the range of the destination type, the result depends on the [overflow-checking context](../statements/checked-and-unchecked.md). In a checked context, an <xref:System.OverflowException> is thrown, while in an unchecked context, the result is an unspecified value of the destination type.
 
 - When you convert `double` to `float`, the `double` value is rounded to the nearest `float` value. If the `double` value is too small or too large to fit into the `float` type, the result is zero or infinity.
 

docs/csharp/language-reference/compiler-options/language.md

@@ -23,13 +23,17 @@ The following options control how the compiler interprets language features. The
 
 ## CheckForOverflowUnderflow
 
-The **CheckForOverflowUnderflow** option specifies whether an integer arithmetic statement that results in a value that is outside the range of the data type causes a run-time exception.  
+The **CheckForOverflowUnderflow** option controls the default overflow-checking context that defines the program behavior in the case of integer arithmetic overflow.
 
 ```xml
 <CheckForOverflowUnderflow>true</CheckForOverflowUnderflow>
 ```
 
-An integer arithmetic statement that is in the scope of a `checked` or `unchecked` keyword isn't subject to the effect of the **CheckForOverflowUnderflow** option. If an integer arithmetic statement that isn't in the scope of a `checked` or `unchecked` keyword results in a value outside the range of the data type, and **CheckForOverflowUnderflow** is `true`, that statement causes an exception at run time. If **CheckForOverflowUnderflow** is `false`, that statement doesn't cause an exception at run time. The default value for this option is `false`; overflow checking is disabled.
+When **CheckForOverflowUnderflow** is `true`, the default context is a checked context and overflow checking is enabled; otherwise, the default context is an unchecked context. The default value for this option is `false`, that is, overflow checking is disabled.
+
+You can also explicitly control the overflow-checking context for the parts of your code by using the `checked` and `unchecked` statements.
+
+For information about how the overflow-checking context affects operations and what operations are affected, see the [article about `checked` and `unchecked` statements](../statements/checked-and-unchecked.md).
 
 ## AllowUnsafeBlocks
 

docs/csharp/language-reference/keywords/checked-and-unchecked.md

@@ -28,7 +28,7 @@ The first table in this topic lists keywords that are reserved identifiers in an
         [`case`](../statements/selection-statements.md#the-switch-statement)  
         [`catch`](try-catch.md)  
         [`char`](../builtin-types/char.md)  
-        [`checked`](checked.md)  
+        [`checked`](../statements/checked-and-unchecked.md)  
         [`class`](class.md)  
         [`const`](const.md)  
         [`continue`](../statements/jump-statements.md#the-continue-statement)  
@@ -94,7 +94,7 @@ The first table in this topic lists keywords that are reserved identifiers in an
         [`typeof`](../operators/type-testing-and-cast.md#typeof-operator)  
         [`uint`](../builtin-types/integral-numeric-types.md)  
         [`ulong`](../builtin-types/integral-numeric-types.md)  
-        [`unchecked`](unchecked.md)  
+        [`unchecked`](../statements/checked-and-unchecked.md)  
         [`unsafe`](unsafe.md)  
         [`ushort`](../builtin-types/integral-numeric-types.md)  
         [`using`](using.md)  

docs/csharp/language-reference/keywords/checked.md

@@ -17,8 +17,6 @@ static async Task Main(string[] args)
             UsingStatements.Examples();
             Console.WriteLine("=================    try-catch Keyword Examples ======================");
             await AsyncExceptionExamples.Examples();
-            Console.WriteLine("=================    try-catch Keyword Examples ======================");
-            CheckedAndUnchecked.Examples();
         }
     }
 }

docs/csharp/language-reference/keywords/index.md

@@ -17,7 +17,7 @@ Statements are program instructions. Except as described in the topics reference
 |[Iteration statements](../statements/iteration-statements.md)|`do`, `for`, `foreach`, `while`|
 |[Jump statements](../statements/jump-statements.md)|`break`, `continue`, `goto`, `return`|
 |Exception handling statements|[throw](throw.md), [try-catch](try-catch.md), [try-finally](try-finally.md), [try-catch-finally](try-catch-finally.md)|
-|[Checked and unchecked](checked-and-unchecked.md)|[checked](checked.md), [unchecked](unchecked.md)|
+|[checked and unchecked statements](../statements/checked-and-unchecked.md)|`checked`, `unchecked`|
 |[fixed statement](fixed-statement.md)|[fixed](fixed-statement.md)|
 |[lock statement](../statements/lock.md)|`lock`|
 |[yield statement](yield.md)|`yield`|