set (C# Reference)
The set keyword defines an accessor method in a property or indexer that assigns a value to the property or the indexer element. For more information and examples, see Properties, Automatically implemented properties, and Indexers.
The following example defines both a get and a set accessor for a property named Seconds. It uses a private field named _seconds to back the property value.
class TimePeriod
{
private double _seconds;
public double Seconds
{
get { return _seconds; }
set
{
if (value < 0)
{
throw new ArgumentOutOfRangeException(nameof(value), "The value of the time period must be non-negative.");
}
_seconds = value;
}
}
}
Often, the set accessor consists of a single statement that assigns a value, as it did in the previous example. You can implement the set accessor as an expression-bodied member. The following example implements both the get and the set accessors as expression-bodied members.
class TimePeriod2
{
private double _seconds;
public double Seconds
{
get => _seconds;
set => _seconds = value;
}
}
For simple cases in which a property's get and set accessors perform no other operation than setting or retrieving a value in a private backing field, you can take advantage of the C# compiler's support for automatically implemented properties. The following example implements Hours as an automatically implemented property.
class TimePeriod3
{
public double Hours { get; set; }
}
Important
Automatically implemented properties aren't allowed for interface property declarations or the implementing declaration for a partial property. The compiler interprets syntax matching an automatically implemented property as the declaring declaration, not an implementing declaration.
C# language specification
For more information, see the C# Language Specification. The language specification is the definitive source for C# syntax and usage.
