C# Hashtable contains byte array value

Question

I am looking for a quick way to find if hashtable (string to byte array) collection values contains a given value, i can't use the given contains as it will compare the array object not its values.

i don't mind using linq / extension / implementing contains as long as it is short.

i have tried:

byte[] givenArr = new[]{1,2,3,4}; //(a given arr)
bool contains=false;
Hashtable table;
foreach(var val in table.values)
  if (CompareBytesFunction((byte[])val,givenArr))
      contains=true;

where compare bytes is a function to compare the 2 given byte arrays, i feel this is not the right approach. there might be a simpler way to get this without the helper method.

can you show us what u have tried we can't start from a simple description — BRAHIM Kamel
– BRAHIM Kamel, Commented Mar 30, 2014 at 13:17
There is no other way than iterating over the byte array looking for your byte(s). — Sam Leach
– Sam Leach, Commented Mar 30, 2014 at 13:25

score 2 · Accepted Answer · 2014-03-30 13:32:48Z

2

Even though it's pretty much against the concept of Hashtables which should be searched by key, you can use such code:

//suppose this is the byte array you're looking for:
byte[] b = new byte[] { 1, 3, 5 };

bool exists = myHashtable.Values.OfType<byte[]>().
    ToList().Exists(c => c.SequenceEqual(b));

edited Mar 30, 2014 at 13:32

answered Mar 30, 2014 at 13:27

user447356

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15 Comments

Selman Genç Over a year ago

why you are calling ToList after Cast and OfType ?

Alexandre Pepin Over a year ago

Simpler version : myHashtable.Values.Cast<byte[]>().ToList().Exists(c => c.SequenceEqual(b));

josh Over a year ago

Great, exactly what i needed, also protects me from exception in case table was modified in the process. (my solution will throw exception in such a case)

user447356 Over a year ago

@Selman22 was able to optimize a bit, but IEnumerable doesn't have the .Exists() method that I originally wanted so I fear one .ToList() is still needed. :(

Alexandre Pepin Over a year ago

@josh This solution will also throw an exception if another thread modifies the table.

|

usr · Accepted Answer · 2014-03-30 13:57:10Z

0

You should probably implement an IEqualityComparer that can hash and compare byte[]. Then you can just use the normal hashtable methods.

answered Mar 30, 2014 at 13:57

usr

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