Ref and Out

What is Ref & Out?

class Program {     public static void Calc(int a, int b, ref int x, ref int y, ref int z)     {         x = a + b;         y = a - b;         z = a * b;     }     static void Main(string[] args)     {         int p, q, sum, sub, mul;         p = 5;         q = 10;         sum = 0;      //  in case of ref we have to initialize         sub = 0;      //  variables whose reference is passing to function         mul = 0;      //  before passing reference to function         Calc(p, q, ref sum, ref sub, ref mul);         Console.WriteLine("Sum: {0}", sum);         Console.WriteLine("Sub: {0}", sub);         Console.WriteLine("Mul: {0}", mul);         Console.ReadKey();     } }

class Program {     public static void Calc(int a, int b, out int x, out int y, out int z)     {         x = a + b;  //  we have to initialize in the         y = a - b;  //  function         z = a * b;  //      }     static void Main(string[] args)     {         int p, q, sum, sub, mul;         p = 5;         q = 2;         //sum = 0;      //  in case of out we don't need to initialize         //sub = 0;      //  variables whose reference is passing to function but         //mul = 0;      //  the calling function have to intialize that reference         Calc(p, q, out sum, out sub, out mul);         Console.WriteLine("Sum: {0}", sum);         Console.WriteLine("Sub: {0}", sub);         Console.WriteLine("Mul: {0}", mul);         Console.ReadKey();     } }