C # Action in Foreach

Question

fMethodis Action<Fruit>.

But when called fMethod, the parameter is always the last record _Fruits.
How to solve this?

foreach(Fruit f in _Fruits)
{
   field.Add(new Element(f.ToString(),delegate{fMethod(f);}));
}

+5

user1868675 Mar 31 '13 at 12:05

2 answers

Try using a temporary variable.

foreach(Fruit f in _Fruits)
{
   var temp = f;
   field.Add(new Element(temp.ToString(),delegate{fMethod(temp);}));
}

+1

scartag Mar 31 '13 at 12:10

dasblinkenlight · Accepted Answer · 2013-03-31T12:10:01+0000

This is a well-known problem using a modified sentence in a call that a delegate creates. Adding a temporary variable should solve this problem:

foreach(Fruit f in _Fruits)
{
    Fruit tmp = f;
    field.Add(new Element(f.ToString(),delegate{fMethod(tmp);}));
}

This issue has been fixed in C # 5 ( see Eric Lippert's blog ).