Hash from two arrays: Difference between revisions

Content added Content deleted

Inline

@@ Line 324: / Line 324: @@
 =={{header|C sharp}}==
+===C# 1.0===
-<lang csharp>System.Collections.HashTable h = new System.Collections.HashTable();
+<lang csharp>static class Program
+{
+    static void Main()
+    {
+        System.Collections.Hashtable h = new System.Collections.Hashtable();
-string[] arg_keys = {"foo","bar","val"};
+        string[] keys = { "foo", "bar", "val" };
-string[] arg_values = {"little", "miss", "muffet"};
+        string[] values = { "little", "miss", "muffet" };
-//Some basic error checking
-int arg_length = 0;
-if ( arg_keys.Length == arg_values.Length ) {
-  arg_length = arg_keys.Length;
-}
+        System.Diagnostics.Trace.Assert(keys.Length == values.Length, "Arrays are not same length.");
-for( int i = 0; i < arg_length; i++ ){
-  h.add( arg_keys[i], arg_values[i] );
+        for (int i = 0; i < keys.Length; i++)
+        {
+            h.Add(keys[i], values[i]);
+        }
+    }
 }</lang>
+<code>Hashtable.Add</code> throws an exception when a key already exists.
-Alternate way of adding values
+An alternative method to add entries is to use the indexer setter, which replaces the old value associated with a key, if any:
+<lang csharp>h[keys[i]] = values[i];</lang>
+===Modern===
+Uses <code>System.Collections.Generic.Dictionary<TKey, TValue></code>, <code>Enumerable.ToDictionary</code> from LINQ, extension method syntax, and lambda expressions.
+<code>Enumerable.Zip</code> truncates the longer of its arguments.
+<lang csharp>using System.Linq;
+static class Program
+{
+    static void Main()
+    {
+        string[] keys = { "foo", "bar", "val" };
+        string[] values = { "little", "miss", "muffet" };
+        var h = keys
-<lang csharp>for( int i = 0; i < arg_length; i++ ){
+            .Zip(values, (k, v) => (k, v))
-  h[ arg_keys[i] ] = arg_values[i];
+            .ToDictionary(keySelector: kv => kv.k, elementSelector: kv => kv.v);
+    }
 }</lang>