Compiler Error CS0269

Use of unassigned out parameter 'parameter'

The compiler could not verify that the out parameter was assigned a value before it was used; its value may be undefined when assigned. Be sure to assign a value to out parameters in the called method before accessing the value. If you need to use the value of the variable passed in, use a ref parameter instead. For more information, see Method Parameters.

Example 1

The following sample generates CS0269:

C#

// CS0269.cs  
class C  
{  
    public static void F(out int i)  
    // One way to resolve the error is to use a ref parameter instead  
    // of an out parameter.  
    //public static void F(ref int i)  
    {  
        // The following line causes a compiler error because no value  
        // has been assigned to i.  
        int k = i;  // CS0269  
        i = 1;  
        // The error does not occur if the order of the two previous
        // lines is reversed.  
    }  
  
    public static void Main()  
    {  
        int myInt = 1;  
        F(out myInt);  
        // If the declaration of method F is changed to require a ref  
        // parameter, ref must be specified in the call as well.  
        //F(ref myInt);  
    }  
}  

Example 2

This could also occur if the initialization of a variable occurs in a try block, which the compiler is unable to verify will execute successfully:

C#

// CS0269b.cs  
class C  
{  
    public static void F(out int i)  
    {  
        try  
        {  
            // Assignment occurs, but compiler can't verify it  
            i = 1;  
        }  
        catch  
        {  
        }  
  
        int k = i;  // CS0269  
        i = 1;  
    }  
  
    public static void Main()  
    {  
        int myInt;  
        F(out myInt);  
    }  
}