C# 9.0 - What is an init-only setter?

Answer

This interview question shows the developer's understanding of C# features.

This construct provides a clear, concise way of initializing a property. Properties defined in this way are read-only once defined. Attempting to change the property will result in a compiler error.

	// Define a struct with the init setter
        public struct Product
        {
            public decimal Price { get; init; }
            public string ProductName{ get; init; }
            public string SKU { get; init; }
 
        }

	 // compiles fine
            var shampoo = new Product
            {

                Price = 4.99M,
                ProductName = "My Excellent Shampoo",
                SKU = "FFH2209"
            };

	// Trying to change any of the properties after construction will result in an error as shown below

	//Severity Code    Description Project File Line    Suppression State
        //Error CS8852  Init - only property or indexer 'Program.Product.SKU' can only be assigned in an object 	 
        //initializer, or on 'this' or 'base' in an instance constructor or an 	     
       //'init' accessor.Active

	shampoo.SKU = "FFLXI220";

Written by on May 17th, 2021

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How to Answer: C# 9.0 - What is an init-only setter?

Advice and answer examples written specifically for a C# Advanced job interview.

3. C# 9.0 - What is an init-only setter?

This interview question shows the developer's understanding of C# features.

This construct provides a clear, concise way of initializing a property. Properties defined in this way are read-only once defined. Attempting to change the property will result in a compiler error.

	// Define a struct with the init setter
        public struct Product
        {
            public decimal Price { get; init; }
            public string ProductName{ get; init; }
            public string SKU { get; init; }
 
        }

	 // compiles fine
            var shampoo = new Product
            {

                Price = 4.99M,
                ProductName = "My Excellent Shampoo",
                SKU = "FFH2209"
            };

	// Trying to change any of the properties after construction will result in an error as shown below

	//Severity Code    Description Project File Line    Suppression State
        //Error CS8852  Init - only property or indexer 'Program.Product.SKU' can only be assigned in an object 	 
        //initializer, or on 'this' or 'base' in an instance constructor or an 	     
       //'init' accessor.Active

	shampoo.SKU = "FFLXI220";

Written by Edward Danganan on April 21st, 2021

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