How to compare arrays in C

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Possible Duplicate    Easiest way to compare arrays in C        How can I compare two arrays in C    I use the following code  but its result is false  I was expecting it to be true   Array Equals childe1 grandFatherNode

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You re comparing the object references  and they are not the same  You need to compare the array contents    NET2 solution  An option is iterating through the array elements and call Equals   for each element  Remember that you need to override the Equals   method for the array elements  if they are not the same object reference   An alternative is using this generic method to compare two generic arrays   static bool ArraysEqual lt T gt  T   a1  T   a2        if  ReferenceEquals a1  a2           return true       if  a1    null    a2    null          return false       if  a1 Length    a2 Length          return false       var comparer   EqualityComparer lt T gt  Default      for  int i   0  i  lt  a1 Length  i                  if   comparer Equals a1 i   a2 i    return false            return true       NET 3 5 or higher solution  Or use SequenceEqual if Linq is available for you   NET Framework    3 5

User · Answer

The Equals method does a reference comparison - if the arrays are different objects  this will indeed return false   To check if the arrays contain identical values  and in the same order   you will need to iterate over them and test equality on each

User · Answer

Array Equals   appears to only test for the same instance   There doesn t appear to be a method that compares the values but it would be very easy to write   Just compare the lengths  if not equal  return false  Otherwise  loop through each value in the array and determine if they match

User · Answer

There is no static Equals method in the Array class  so what you are using is actually Object Equals  which determines if the two object references point to the same object   If you want to check if the arrays contains the same items in the same order  you can use the SequenceEquals extension method   childe1 SequenceEqual grandFatherNode    Edit   To use SequenceEquals with multidimensional arrays  you can use an extension to enumerate them  Here is an extension to enumerate a two dimensional array   public static IEnumerable lt T gt  Flatten lt T gt  this T    items      for  int i   0  i  lt  items GetLength 0   i        for  int j   0  j  lt  items GetLength 1   j          yield return items i  j       Usage   childe1 Flatten   SequenceEqual grandFatherNode Flatten      If your array has more dimensions than two  you would need an extension that supports that number of dimensions  If the number of dimensions varies  you would need a bit more complex code to loop a variable number of dimensions   You would of course first make sure that the number of dimensions and the size of the dimensions of the arrays match  before comparing the contents of the arrays   Edit 2   Turns out that you can use the OfType lt T gt  method to flatten an array  as RobertS pointed out  Naturally that only works if all the items can actually be cast to the same type  but that is usually the case if you can compare them anyway  Example   childe1 OfType lt Person gt    SequenceEqual grandFatherNode OfType lt Person gt

User · Answer

Array Equals is comparing the references  not their contents      Currently  when you compare two arrays with the   operator  we are really using the System Object s   operator  which only compares the instances   i e  this uses reference equality  so it will only be true if both arrays points to the exact same instance     Source  If you want to compare the contents of the arrays you need to loop though the arrays and compare the elements   The same blog post has an example of how to do this

User · Answer

You can use the Enumerable SequenceEqual   in the System Linq to compare the contents in the array  bool isEqual   Enumerable SequenceEqual target1  target2

[c#] How to compare arrays in C#?

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