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document null wrt pattern matching #5868

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Jun 15, 2018
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document null wrt pattern matching #5868

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4ef7e9f
document null wrt pattern matching
IanKemp Jun 8, 2018
e8a9eb4
lift condition on expr being null
BillWagner Jun 15, 2018
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4 changes: 2 additions & 2 deletions docs/csharp/language-reference/keywords/is.md
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Expand Up @@ -69,7 +69,7 @@ When using the type pattern to perform pattern matching, `is` tests whether an e

where *expr* is an expression that evaluates to an instance of some type, *type* is the name of the type to which the result of *expr* is to be converted, and *varname* is the object to which the result of *expr* is converted if the `is` test is `true`.

The `is` expression is `true` if any of the following is true:
The `is` expression is `true` if *expr* is not `null`, and any of the following is true:

- *expr* is an instance of the same type as *type*.

Expand All @@ -79,7 +79,7 @@ The `is` expression is `true` if any of the following is true:

- *expr* is an instance of a type that implements the *type* interface.

If *exp* is `true` and `is` is used with an `if` statement, *varname* is assigned and has local scope within the `if` statement only.
If *expr* is `true` and `is` is used with an `if` statement, *varname* is assigned and has local scope within the `if` statement only.

The following example uses the `is` type pattern to provide the implementation of a type's <xref:System.IComparable.CompareTo(System.Object)?displayProperty=nameWithType> method.

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