I would like to have something like tkis "int?" but for string. You know if I will not give data to parameter I will not got error. I need some idea to this problem.
Example(4);
public void Example(int, string?){}
For all of you I give points. Thanks for help. Topic [closed] :)
This isn't available as string is already a reference type, so is already nullable. The ? suffix is syntactic sugar for Nullable<T>, so int? is equivalent to Nullable<int>... and Nullable<T> has a constraint of where T : struct, i.e. T has to be a non-nullable value type... which excludes string.
In other words, you can just write
public void Example(int x, string y)
{
if (y == null)
{
...
}
}
Note that this is different from making it an optional parameter. Passing in a null value is still passing in a value. If you want to make it an optional parameter you can do that too:
public void Example(int x, string y = "Fred")
...
Example(10); // Equivalent to Example(10, "Fred");
if (x == null) but with a warning :)System.String is a reference type, so you can assign to a String variable null without declaring the variable nullable.
string type take null by default and you do not need to make it nullable as it is already reference type. You can use it this way.
public void Example(int i, string s)
{
}
Call it with null will be
Example(null, null);
In C# 4.0 you can use optional parameters by writing
public void Example (int a, string b = null) {}
Otherwise, you can overload the method
public void Example (int a) {}
public void Example (int a, string b) {}
Do you need to give the string argument a default value?
e.g.
Example(4);
public void Example(int x, string y = null)
{
// etc
}
string?.