What is the difference between out and ref in C#?
There is a big difference between
The following sample C# program uses both the
There is a big difference between
ref and out parameters at the language level. Before you can pass a ref
parameter, you must assign it to a value. This is for the purpose of
definite assignment analysis. On the other hand, you don't need to
assign an out parameter before passing it to a method. However, the out parameter in that method must assign the parameter before returning.
The following sample C# program uses both the
ref and out parameter types,its enough for you to understand the actual difference between ref and out keywords:
using System;
class Program
{
static void SetStringRef (ref string value)
{
if (value == "cat") // Test parameter value
{
Console.WriteLine ("cat");
}
value = "dog"; // Assign parameter to new value
}
static void SetStringOut (int number, out string value)
{
if (number == 1) // Check int parameter
{
value = "one"; // Assign out parameter
}
else
{
value = "other"; // Assign out parameter
}
}
static void Main()
{
string value1 = "cat"; // Assign string value
SetStringRef (ref value1); // Pass as reference parameter
Console.WriteLine (value1); // Write result
string value2; // Unassigned string
SetStringOut (1, out value2);// Pass as out parameter
Console.WriteLine (value2); // Write result
}
}
see out put:}
| ref and out usage examples | (program output) |
| cat
dog one |
