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guide/english/csharp/null-conditional-operator/index.md

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+---
+title: Null-conditional Operator
+---
+
+# Null-conditional Operator
+
+Null-conditional operators allow for null checking with a minimal amount of code. For example, if you had
+an employee variable of type Employee with a property of type Address, you might do null checking as follows:
+
+```csharp
+Address address = null;
+if (employee != null)
+{
+    address = employee.Address;
+}
+```
+
+You could use a standard conditional operator to make that check more concise:
+
+```csharp
+Address address = employee != null ? employee.Address : null;
+```
+
+However, in C# 6.0 null-conditional operators were introduced, so now the above line can simply
+be represented as follows:
+
+```csharp
+Address address = student?.Address;
+```
+
+If employee is null, address will simply be assigned null, and no NullReferenceExeception will occur.
+This becomes more useful with deeper object graphs, as you can handle a chain of conditional member access.
+
+For example:
+```csharp
+string city = student?.Address?.City;
+```
+
+Null-conditional operators are short-circuiting, so as soon as one check of conditional member access
+returns null, the rest do not take place.
+
+# Null-coalescing operator
+Another useful null-checking option is the null-coalescing operator. It returns the left-hand operand if the operand is not null; otherwise it returns the right hand operand.
+
+For example:
+```csharp
+public string GetStringValue()
+{
+    return null;
+}
+
+// Display the value of s if s is NOT null. If x IS null, display the string "It was null."
+
+string x = GetStringValue();
+
+Console.WriteLine(x ?? "It was null.");
+
+// Result:
+
+"It was null."
+```