init (C# Reference)
In C# 9 and later, the init keyword defines an accessor method in a property or indexer. An init-only setter assigns a value to the property or the indexer element only during object construction. For more information and examples, see Properties, Auto-Implemented Properties, and Indexers.
The following example defines both a get and an init accessor for a property named Seconds. It uses a private field named _seconds to back the property value.
class InitExample
{
private double _seconds;
public double Seconds
{
get { return _seconds; }
init { _seconds = value; }
}
}
Often, the init accessor consists of a single statement that assigns a value, as it did in the previous example. You can implement the init accessor as an expression-bodied member. The following example implements both the get and the init accessors as expression-bodied members.
class InitExampleExpressionBodied
{
private double _seconds;
public double Seconds
{
get => _seconds;
init => _seconds = value;
}
}
For simple cases in which a property's get and init 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 auto-implemented properties. The following example implements Hours as an auto-implemented property.
class InitExampleAutoProperty
{
public double Hours { get; init; }
}
C# language specification
For more information, see the C# Language Specification. The language specification is the definitive source for C# syntax and usage.