Необходимо возвратить это как IntPtr. Возврат Системы. Строковый тип от функции PInvoke требует большого ухода. CLR должен передать память от собственного представления в управляемое. Это - легкая и предсказуемая операция.
проблема, хотя идет, что сделать с собственной памятью, которая была возвращена из нечто (). CLR принимает следующие два объекта о функции PInvoke, которая непосредственно возвращает строковый тип
Поэтому, это упорядочит строку и затем назовет CoTaskMemFree на собственном блобе памяти. Если Вы на самом деле не выделили эту память с CoTaskMemAlloc, это в лучшем случае вызовет катастрофический отказ в Вашем приложении.
для получения корректной семантики здесь необходимо возвратить IntPtr непосредственно. Тогда используйте Маршала. PtrToString* для получения до управляемого Строкового значения. Вы, возможно, все еще должны освободить собственную память, но это будет зависящий от реализации нечто.
Try this:
// This returns an instance of type "Foo",
// since I didn't know the type of "list".
// Obviously the return type would need to
// match the type of whatever "list" contains.
public Foo this[int index]
{
get { return list[index]; }
set { list[index] = value; }
}
This is C#'s indexer syntax and it has some limitations (it's not as flexible as VB.NET's parameterful properties) but it does work for your specific example.
As others have shown, you can turn it into an indexer - which can have multiple parameters, by the way.
What you can't do is name an indexer in C#... although you can in VB. So you can't have two indexers, one called Foo
and the other called Bar
... you'd need to write properties which returned values which were themselves indexable. It's a bit of a pain, to be honest :(
This is called indexer property
public int this [int index]
{
get { return list[index]; }
set { list[index] = value; }
}
I think what you might be looking for is:
public Something this[int index]
{
get
{
return list[index];
}
set
{
list[index] = value;
}
}
For the record, Whilst the other answers are valid, you might also want to consider using the following approach:
public IList<Something> items { get; set; }
This could then be used as follows:
Something item = myFoo.items[1];
The other answers would be used in the following, slightly different, way:
Something item = myFoo[1];
The one you want depends on what exactly you are trying to achieve, which is difficult to determine without seeing the rest of the code.
Besides the indexer that has been mentioned several times now, another possibility is to make a custom class with an indexer and return an instance of it as a property.
Example:
public class IntList
{
public IntList(IEnumerable<int> source)
{
items = source.ToArray();
Squares = new SquareList(this);
}
private int[] items;
// The indexer everyone else mentioned
public int this[int index]
{
get { return items[index]; }
set { items[index] = value; }
}
// Other properties might be useful:
public SquareList Squares { get; private set; }
public class SquareList
{
public SquareList(IntList list)
{
this.list = list;
}
private IntList list;
public int this[int index]
{
get { return list.items[index] * list.items[index]; }
}
}
}
You can use indexator for solving this problem
public object this[string name]
{
get
{
int idx = FindParam(name);
if (idx != -1)
return _params[idx].Value;
throw new IndexOutOfRangeException(String.Format("Parameter \"{0}\" not found in this collection", name));
}
set
{
int idx = FindParam(name);
if (idx != -1)
_params[idx].Value = value;
else
throw new IndexOutOfRangeException(String.Format("Parameter \"{0}\" not found in this collection", name));
}
}