.net - C# Struct method doesn't save value if accessed by a property -

i need create structure looks int (but has field need...), created new structure named teststruct added 1 method (test()) needed , overloaded operators, , seemed working well...

the sample below shows problem. if structure test() method executed val property val property seems lose value, if method executed on val2 variable, 1 seems keep right value...

why happen?

static class program {     /// <summary>     /// main entry point application.     /// </summary>     [stathread]     static void main()     {         new testclass();     } }  public class testclass {     public teststruct val { get; set; }     private teststruct val2;      public testclass()     {         val.test();         console.writeline(val + "-> why not 10?");          //direct assignment works well...         val = 123;         console.writeline(val  + "-> direct assingment works..");          //this way works too. why doesn't work "get;" , "set;"?         val2.test();         console.writeline(val2 + "-> works way");     } }  public struct teststruct {     private int32 _value;     public long offset { get; set; }      public static implicit operator teststruct(int32 value)     {         return new teststruct { _value = value };     }      public static implicit operator int32(teststruct value)     {         return value._value;     }      public void test()     {         _value = 10;     } } 

your struct wrong.

for large number of reasons, should never make mutable struct.

just int or datetime value immutable , can never change, specific value of struct must never change @ all.

instead, can make functions return new, different value .

here reasons mutable structs evil:

1. http://ericlippert.com/2008/05/14/mutating-readonly-structs/
2. http://blog.slaks.net/2010/12/when-shouldnt-you-write-ref-this.html
3. http://codeblog.jonskeet.uk/2010/07/27/iterate-damn-you/
4. http://philosopherdeveloper.wordpress.com/2011/03/31/how-i-discovered-a-bug-in-the-c-compiler-part-1/

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to answer question, val.test() equivalent get_val().test().
since structs value types, `get_val() (the automatically-generated property getter) returns copy of struct.
original struct in private backing field not affected.