C# : Check if two objects have same data

Question

Assuming that Obj1 and Obj2 are objects of the same class and the class contains only fields, is it possible to check whether the two objects have the same data if the fields of the class are not known?

Pretty sure this isn't possible without knowing the names of the fields. I may be wrong though — User1, Aug 01 '14 at 09:47
It is possible. Writing answer now (clue, it involves reflection). — , Aug 01 '14 at 09:47
possible duplicate of [Comparing two objects by iterating recursively through all the properties' properties?](http://stackoverflow.com/questions/25062428/comparing-two-objects-by-iterating-recursively-through-all-the-properties-prope) — Adriano Repetti, Aug 01 '14 at 09:50
Using Reflection or BinaryFormatter to compare serialized raw byte[] arrays. — Adriano Repetti, Aug 01 '14 at 09:51
possible duplicate of [Compare the content of two objects for equality](http://stackoverflow.com/questions/375996/compare-the-content-of-two-objects-for-equality) — frank koch, Aug 01 '14 at 10:03

score 7 · Accepted Answer · answered Aug 01 '14 at 09:50

7

var haveSameData = false;

foreach(PropertyInfo prop in Obj1.GetType().GetProperties())
{
    haveSameData = prop.GetValue(Obj1, null).Equals(prop.GetValue(Obj2, null));

    if(!haveSameData)
       break;
}

This is based on assumptions (objects are of the same type), and could probably be refactored so that it's more defensive, but I'm keeping it readable so you can grasp what I'm trying to do.

In a nutshell, use reflection to iterate over the fields and check the values of each until satisfied that they don't match (no need to keep iterating after this).

answered Aug 01 '14 at 09:50

The typeof() function is not necessary in the example. Other than that, this is a well-reasoned straight-forward sample. I might also replace the "==" operator with ".Equals()" instead to avoid reference comparisons. Cheers! – Rob Epstein Aug 01 '14 at 09:53
Edited accordingly. Thanks. – Aug 01 '14 at 09:54
An exercise for "Coding man" may be to handle complex property types such as generic lists. – Rob Epstein Aug 01 '14 at 09:55
@RobEpstein: yes, I will try some time :) – Coding man Aug 01 '14 at 10:08
question said class only contains fields and not properties. Confused why your answer got accepted – Felix Keil Aug 01 '14 at 10:59

score -4 · Answer 2 · answered Aug 01 '14 at 09:53

-4

Try this assert:

CollectionAssert.AreEqual(Obj1, Obj2);

answered Aug 01 '14 at 09:53

Thanos Markou

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This would be good but it compares objects that implement `ICollection` only. – Aug 01 '14 at 09:55
This will use the built in .net Equal methods which will do a referential equality check. – Philip Pittle Aug 01 '14 at 12:19

C# : Check if two objects have same data

2 Answers2