When using a dictionary you can do the following:
Hashtable
hashtable = new
Hashtable();
string test;
test = (string)hashtable[
"a"];
// test is “a”test = (string)hashtable[
"c"];
// test is null
However, when converting this to a generic dictionary, it has a different expected behaviour:
Dictionary
<string, string> dictionary = new
Dictionary<string, string>();
string test;
test = dictionary[
"a"];
// test is “a”test = dictionary[
"c"];
// throws KeyNotFoundException’
You can either do this:
Dictionary<string, string> dictionary = new Dictionary<string, string>();
string test;
try
{
test = dictionary["c"]; // throws KeyNotFoundException’
}
catch
{
test = null;
}
or use the more generic approach:
dictionary.TryGetValue( "c", out test ); // test is null
If the key is not found, then the value parameter gets the appropriate default value for the value type V;
for example, zero (0) for integer types, false for Boolean types, and null for reference types.
