C sharp structs

mukul chakravarty

I have two questions:-

1. Why is it that in c sharp structure, the default constructor is responsible for initializing our fields and we cannot initialize them by ourselves ??

2. Why is that if we declare a parametrized constructor or a method inside a structure then we have to initialize our fields inside it ??

3 Replies

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Vulpes13y ago
Well, performance is the reason why C# (and .NET generally) has structs in the first place.

This behavior is just a corollary of structs being value types, the need for all types to have a sensible default value and the need to ensure that all fields are assigned a definite value before they are used.
mukul chakravarty13y ago
Is performance the reason behind this behavior of structures ???
Vulpes13y ago
1. All structs have a default value which consists of setting the bytes of all their instance fields to 0. This means that all value type fields of the struct are set to their default values (0 for numbers and enums, false for bool, '\0' for char) and all reference type fields are set to null.

Also all structs have a default parameterless constructor which sets the fields to their default values and can't be overridden by the programmer.

Consequently, you're not allowed to set instance fields to something else when they're declared which would produce unexpected behavior.

2. Because of #1 above the only way to set the instance fields of a struct to something other than their default values is to use a constructor which takes parameters. Moreover, to make sure that the fields have been 'definitely assigned', the C# compiler insists that all instance fields are assigned a value (even if its only the default value) by the time the constructor ends and before any instance method or property of the struct can be accessed.

Notice that none of this applies to static fields of a struct which can be assigned non-default values when they're declared.