Difference between Ref and Out keywords in C#

In this article we will see what is the Difference between Ref and Out keywords in C#

Here is the simple example to show you the difference between Ref and Out in C#

class Program
    {
        static void Main(string[] args) //calling method
        {
            int valref = 0; //must be initialized
            int valout; //not compulsary

            method1(ref valref);
            Console.WriteLine(valref);

            method2(out valout);
            Console.WriteLine(valout);

            Console.ReadLine();
        }
        static void method1(ref int value) //called method
        {
            value = 1; //not compulsary to initialize 
        }
        static void method2(out int value) //called method
        {
            value = 2; //must be initialized
        }
    }

Below are some differences:

Ref:

• Must initialized before passing to its called method
• This is bi-directional
• The value of the ref parameter can be changed before passing to its calling method.

Out: 

• Not compulsory to initialize before passing to the method
• This is uni-directional
• The value initialized for the Out parameter in the called method will be returned to its calling method.