Use pattern matching in code sample (#9626)

drewnoakes · web-flow · commit 506c2906b61d · 2024-02-19T15:15:35.000-08:00
The `null != ...` check looked strange, as it's usually written the other way around in C#. Rather than have a null check, just change this to a type check.
diff --git a/xml/System.Security.Claims/ClaimsPrincipal.xml b/xml/System.Security.Claims/ClaimsPrincipal.xml
@@ -95,8 +95,7 @@
  The following example extracts the claims presented by a user in an HTTP request and writes them to the HTTP response. The current user is read from the <xref:System.Web.HttpContext> as a <xref:System.Security.Claims.ClaimsPrincipal>. The claims are then read from it and then are written to the response.  
   
 ```csharp
-ClaimsPrincipal principal = HttpContext.Current.User as ClaimsPrincipal;  
-if (null != principal)  
+if (HttpContext.Current.User is ClaimsPrincipal principal)  
 {  
    foreach (Claim claim in principal.Claims)  
    {  

Original file line number	Diff line number	Diff line change
`@@ -95,8 +95,7 @@`
`95`	`95`	`The following example extracts the claims presented by a user in an HTTP request and writes them to the HTTP response. The current user is read from the <xref:System.Web.HttpContext> as a <xref:System.Security.Claims.ClaimsPrincipal>. The claims are then read from it and then are written to the response.`
`96`	`96`
`97`	`97`	```csharp
`98`		`-ClaimsPrincipal principal = HttpContext.Current.User as ClaimsPrincipal;`
`99`		`-if (null != principal)`
	`98`	`+if (HttpContext.Current.User is ClaimsPrincipal principal)`
`100`	`99`	`{`
`101`	`100`	`foreach (Claim claim in principal.Claims)`
`102`	`101`	`{`