c# - Keep differences between two hashtables -

i making function compares 2 hashtables , want keep difference of these tables. if both contain 100 keys , 2 have been altered want new hashtable equal 2 differences.

here have. lost on how (keep differences)

private hashtable comparehashtables(hashtable ht1, hashtable ht2) {     hashtable resultsofcompare = new hashtable();     foreach (dictionaryentry entry in ht1)     {         if (ht2.containskey(entry.key) && ht2.containsvalue(entry.value) == false)         {             //keep differences          }     }     return resultsofcompare; } 

it seems want check both key , value equality. if both don't match it's considered difference. creates bit of problem because type of difference can't represented in hash table. consider following

• ht1: key = "bob" value = 42
• ht2: key = "bob" value = 13

here key same value difference. store every difference resulting structure need able contain 2 different values same key. that's not possible hashtable. arraylist of entries differ may better choice exercise.

really there 3 cases consider

1. both tables contain same key have different values
2. left table has key not right
3. right table has key not left

items 2 , 3 can collapsed it's harder collapse 1 bag. need data structure instruct difference in table

struct difference {    internal readonly bool isvaluedifferent;    internal readonly object key;   internal readonly object value;   internal readonly object othervalue;    internal difference(object key, object value) {      key = key;     value = value;     isvaluedifferent = false;   }    internal difference(object key, object value, object othervalue) {      key = key;     value = value;     othervalue = othervalue;     isvaluedifferent = true;   } } 

with can represent cases.

private hashtable comparehashtables(hashtable ht1, hashtable ht2) {   arraylist difflist = new arraylist();   foreach (dictionaryentry entry in ht1) {     object value = ht2[entry.key];     if (value == null) {        difflist.add(new difference(entry.key, entry.value));     } else if (!value.equals(entry.value)) {       difflist.add(new difference(entry.key, entry.value, value));     }   }    foreach (dictionaryentry entry in ht2) {     object value = ht1[entry.key];     if (value == null) {       difflist.add(new difference(entry.key, entry.value));     }   }    return difflist; } 

note: hashtable , arraylist deprecated @ point. why not use dictionary<tkey, tvalue> , list<t> instead?