add iformattable interface (dotnet#4617)

Author: gewarren

xml/System/IntPtr.xml

@@ -86,20 +86,20 @@
     <remarks>
       <format type="text/markdown"><![CDATA[  
   
-## Remarks  
+## Remarks
+
  The <xref:System.IntPtr> type is designed to be an integer whose size is platform-specific. That is, an instance of this type is expected to be 32-bits on 32-bit hardware and operating systems, and 64-bits on 64-bit hardware and operating systems.  
   
- The <xref:System.IntPtr> type can be used by languages that support pointers, and as a common means of referring to data between languages that do and do not support pointers.  
+ The <xref:System.IntPtr> type can be used by languages that support pointers and as a common means of referring to data between languages that do and do not support pointers.  
   
  <xref:System.IntPtr> objects can also be used to hold handles. For example, instances of <xref:System.IntPtr> are used extensively in the <xref:System.IO.FileStream?displayProperty=nameWithType> class to hold file handles.  
   
  The <xref:System.IntPtr> type is CLS-compliant, while the <xref:System.UIntPtr> type is not. Only the <xref:System.IntPtr> type is used in the common language runtime. The <xref:System.UIntPtr> type is provided mostly to maintain architectural symmetry with the <xref:System.IntPtr> type.  
   
- This type implements the <xref:System.Runtime.Serialization.ISerializable> interface.  
-  
-   
+ This type implements the <xref:System.Runtime.Serialization.ISerializable>, and, in .NET 5.0 and later, the <xref:System.IFormattable> interfaces.
   
-## Examples  
+## Examples
+
  The following example uses managed pointers to reverse the characters in an array. After it initializes a <xref:System.String> object and gets its length, it does the following:  
   
 1.  Calls the <xref:System.Runtime.InteropServices.Marshal.StringToHGlobalAnsi%2A?displayProperty=nameWithType> method to copy the Unicode string to unmanaged memory as an ANSI (one-byte) character. The method returns an <xref:System.IntPtr> object that points to the beginning of the unmanaged string. The Visual Basic example uses this pointer directly; in the C++ and C# examples, it is cast to a pointer to a byte.  
@@ -374,9 +374,7 @@
 ## Remarks  
  The <xref:System.IntPtr.Add%2A> method does not throw an exception if the result is too large to represent as a pointer on the specified platform. Instead, the addition operation is performed in an unchecked context.  
   
- Languages that do not support operator overloading or custom operators can use this method to add an offset to the value of a pointer.  
-  
-   
+ Languages that do not support operator overloading or custom operators can use this method to add an offset to the value of a pointer.
   
 ## Examples  
  The following example instantiates an <xref:System.IntPtr> object that points to the beginning of a ten-element array, and then calls the <xref:System.IntPtr.Add%2A> method to iterate the elements in the array.  
@@ -1532,9 +1530,7 @@
 ## Remarks  
  The <xref:System.IntPtr.Subtract%2A> method does not throw an exception if the result is too small to represent as a pointer on the specified platform. Instead, the subtraction operation is performed in an unchecked context.  
   
- Languages that do not support operator overloading or custom operators can use this method to subtract an offset from the value of a pointer.  
-  
-   
+ Languages that do not support operator overloading or custom operators can use this method to subtract an offset from the value of a pointer.
   
 ## Examples  
  The following example instantiates an <xref:System.IntPtr> object that points to the end of a ten-element array, and then calls the <xref:System.IntPtr.Subtract%2A> method to iterate the elements in the array in reverse order.  
@@ -2161,7 +2157,7 @@ This member is an explicit interface member implementation. It can be used only
  [!code-vb[System.IntPtr.Zero#2](~/samples/snippets/visualbasic/VS_Snippets_CLR_System/system.intptr.zero/vb/zero4.vb#2)]  
   
 > [!NOTE]
->  Although <xref:System.IntPtr.Zero> is equivalent to `null` for Windows API functions with parameters or return values that can be either pointers or `null`, <xref:System.IntPtr.Zero> is not equivalent to `null`. Passing `null` to the `IntPtr.Zero.Equals` method always returns `false`.  
+> Although <xref:System.IntPtr.Zero> is equivalent to `null` for Windows API functions with parameters or return values that can be either pointers or `null`, <xref:System.IntPtr.Zero> is not equivalent to `null`. Passing `null` to the `IntPtr.Zero.Equals` method always returns `false`.  
   
  You can also test for a `null` return value from Windows API function calls that return either a pointer or a `null` by comparing the returned value with <xref:System.IntPtr.Zero?displayProperty=nameWithType>. For example, the call to the `GetWindow` function in the following example tries to retrieve the handle of a non-existent window. If it were called from unmanaged code, the function would return `null`, but when it is called from managed code, it returns <xref:System.IntPtr.Zero?displayProperty=nameWithType>.  
   

xml/System/UIntPtr.xml

@@ -90,15 +90,16 @@
     <remarks>
       <format type="text/markdown"><![CDATA[  
   
-## Remarks  
+## Remarks
+
  The <xref:System.UIntPtr> type is designed to be an integer whose size is platform-specific. That is, an instance of this type is expected to be 32-bits on 32-bit hardware and operating systems, and 64-bits on 64-bit hardware and operating systems.  
   
 > [!IMPORTANT]
->  The <xref:System.IntPtr> type is CLS-compliant, while the <xref:System.UIntPtr> type is not. Only the <xref:System.IntPtr> type is used in the common language runtime. The <xref:System.UIntPtr> type is provided mostly to maintain architectural symmetry with the <xref:System.IntPtr> type.  
+> The <xref:System.IntPtr> type is CLS-compliant, while the <xref:System.UIntPtr> type is not. Only the <xref:System.IntPtr> type is used in the common language runtime. The <xref:System.UIntPtr> type is provided mostly to maintain architectural symmetry with the <xref:System.IntPtr> type.  
   
  The <xref:System.UIntPtr> type can be used by languages that support pointers, and as a common means of referring to data between languages that do and do not support pointers. <xref:System.UIntPtr> objects can also be used to hold handles.  
   
- This type implements the <xref:System.Runtime.Serialization.ISerializable> interface.  
+ This type implements the <xref:System.Runtime.Serialization.ISerializable>, and, in .NET 5.0 and later, the <xref:System.IFormattable> interfaces.
   
  ]]></format>
     </remarks>
@@ -322,9 +323,7 @@
 ## Remarks  
  The <xref:System.IntPtr.Add%2A> method does not throw an exception if the result is too large to represent as a pointer on the specified platform. Instead, the addition operation is performed in an unchecked context.  
   
- Languages that do not support operator overloading or custom operators can use this method to add an offset to the value of an unsigned pointer.  
-  
-   
+ Languages that do not support operator overloading or custom operators can use this method to add an offset to the value of an unsigned pointer.
   
 ## Examples  
  The following example instantiates a <xref:System.UIntPtr> object that points to the beginning of a ten-element array, and then calls the <xref:System.UIntPtr.Add%2A> method to iterate the elements in the array.  
@@ -1373,9 +1372,7 @@
 ## Remarks  
  The <xref:System.IntPtr.Subtract%2A> method does not throw an exception if the result is too small to represent as a pointer on the specified platform. Instead, the subtraction operation is performed in an unchecked context.  
   
- Languages that do not support operator overloading or custom operators can use this method to subtract an offset from the value of an unsigned pointer.  
-  
-   
+ Languages that do not support operator overloading or custom operators can use this method to subtract an offset from the value of an unsigned pointer.
   
 ## Examples  
  The following example instantiates an <xref:System.IntPtr> object that points to the end of a ten-element array, and then calls the <xref:System.IntPtr.Subtract%2A> method to iterate the elements in the array in reverse order.  
@@ -1910,7 +1907,7 @@ This member is an explicit interface member implementation. It can be used only
 ## Remarks  
  The value of this field is not equivalent to `null`. Use this field to efficiently determine whether an instance of <xref:System.UIntPtr> has been set to a value other than zero.  
   
- For example, assume the variable, uip, is an instance of <xref:System.UIntPtr>. You can determine if it has been set by comparing it to the value returned by a constructor, for example: " `if uip != new UIntPtr(0)...` ". However, invoking a constructor to get an uninitialized pointer is inefficient. It is better to code either " `if uip != UIntPtr.Zero...` ", or " `if !UIntPtr.Zero.Equals(uip)...` ".  
+ For example, assume the variable, uip, is an instance of <xref:System.UIntPtr>. You can determine if it has been set by comparing it to the value returned by a constructor, for example, `if uip != new UIntPtr(0)...`. However, invoking a constructor to get an uninitialized pointer is inefficient. It is better to code either `if uip != UIntPtr.Zero...` or `if !UIntPtr.Zero.Equals(uip)...`.  
   
  ]]></format>
         </remarks>