c# - Setting Property Doesn't Set Its Inner Property -

i took address: http://csharpindepth.com/articles/chapter8/propertiesmatter.aspx , reason not head around it. can explain me why console.writeline(holder.property.value); outputs 0.

void main() {     mutablestructholder holder = new mutablestructholder();     holder.field.setvalue(10);     holder.property.setvalue(10);     console.writeline(holder.field.value); // outputs 10     console.writeline(holder.property.value); // outputs 0 }  struct mutablestruct {     public int value { get; set; }      public void setvalue(int newvalue)     {         value = newvalue;     } }  class mutablestructholder {     public mutablestruct field;     public mutablestruct property { get; set; } } 

class mutablestructholder {     public mutablestruct field;     public mutablestruct property { get; set; } } 

is equivalent

class mutablestructholder {     public mutablestruct field;      private mutablestruct _property;     public mutablestruct property {         { return _property; }        set { _property = value; }     } } 

which equivalent to:

class mutablestructholder {     public mutablestruct field;      private mutablestruct _property;     public mutablestruct getproperty() {         return _property;     }     public void setproperty(mutablestruct value) {         _property = value;     } } 

so, when this:

holder.property.setvalue(10); 

you're doing this:

holder.getproperty().setvalue(10); 

which equivalent to:

mutablestruct temp = holder.getproperty();  temp.setvalue(10); 

and because structs value types, temp copy of underlying _property field, , modification thrown away when goes out of scope (immediately).

this reason avoid mutable structs plague.