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POStruct wrapping value types and giving access with an index
 

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  1. POStruct wrapping value types and giving access with an index
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    <p>I need to encapsulate an fixed array of a user defined value type (let's call it struct2 ) inside an other struct (struct1) but fixed arrays can be declared only for native value types. So i thought to create a third struct (struct wrapper) that has to work as an array of the struct2 by defining the [] operator. So </p> <pre><code> struct Struct2 { int a; int b } struct wrapper { Struct2 str0; Struct2 str1; public Struct2 this[int index] { get { switch ( index ) { case 0: return str0; case 1: return str1; default: return str0; } } } } static void Main() { wrapper wr = new wrapper(); wr[0].a = 123; // i would like to do this but this doesnt work //but if we do like this Struct2 [] arr = new Struct2[5]; arr[0].a = 123 ;// this works , we are effectively modifying the object //contained in the array (not just a copy) } </code></pre> <p>Ok, this code doesn't work because Struct2 is a value type and when the operator returns then it returns a copy and not the actual object str0 contained in it. I would like to access that field using an indexer ! is it possible ? Why it's possible with the Array class ? I know that it's possible by returning a pointer but this involve using the fixed keyword inside the operator definition and i would like to avoid that because the 'array' need to be accessed extensively and i would end up by using the fixed statement 2 times (inside and outsid to keep the address fixed). Also i already considered using pointers by just declaring N adiacent Struct2 fields in Struct1 and using a pointer to the first one as an array but i would prefer to use the wrapper to emulate an array behaviour. Agai , is it possible?</p> <p>Edit It seems that it's not possible to implement a custom array that works with value types(as common arrays do). Btw the nearest solution i could find is this, but as i wrote i would have liked to avoid pointers.</p> <pre><code> struct Struct2 { int a; int b } struct Struct1 { public Struct2 * str2arr ; //this can be avoided public Struct2 str0; //wrapper is not needed anymore as Struct1 is wrapping the Struct2 array by itself //and a pointer is used for indexing operations //struct layout needs to be sequential private Struct2 str1; private Struct2 str2; private Struct2 str3; private Struct2 str4; } static void Main() { Struct1 myStruct = new Struct1(); fixed(myStruct.str2arr = &amp;myStruct.str0) { myStruct.str2arr[1] = 123; } } </code></pre>
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    1. CO1. Array is a reference type... and when you use indexers, you also get a copy of the content if it's a value type. 2. what is your requirement behind this question ?
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    2. COAre you sure ? I think that your point 1 is at least half wrong, i'm going to edit the question adding t he clarification to this.
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    3. COWhere is struct1 in your code example?
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