Working With Ref And Out Parameter In C#

Here we discuss the ref and out parameters in C#. They are basically parameters and we can use it in a different way.

ref parameter

It is used as a call by reference in C#. It is used both places; when we declare a method and when we call the method. The following example will explain how we use the ref parameter in C#. In this example we create a function (cube) and pass a ref parameter in it, now we look at the value before we call the function and after we call the function,

class TryRef  
{  
    public void cube(ref int x)  
    {  
        x= x * x * x;     
    }  
}  
class Program  
{  
    static void Main(string[] args)  
{  
    TryRef tr = new TryRef();  
    int y = 5;  
    Console.WriteLine("The value of y before   
the function call: " + y);  
    tr.cube(ref y);  
    Console.WriteLine("The value of y after the function call: " + y);  
        Console.ReadLine();  
    }  
}

The output will be,

Working With Ref And Out Parameter In C#

Now we take multiple ref parameters in our next program,

class tryref  
{  
    public void mul(ref int i, ref int j)  
    {  
        j = i * j;  
    }  
}  
class Program  
{  
    static void Main(string[] args)  
    {  
        tryref tf = new tryref();  
        int i = 5;  
        int j = 10;  
        Console.WriteLine("The value of i and j before the call :"+i+","+j);  
            tf.mul(ref i, ref j);  
            Console.WriteLine("The value of i and j after the call :" + i + "," + j);  
        Console.ReadLine();  
    }  
}

The output will be,

Working With Ref And Out Parameter In C#

Out parameter

Sometimes we do not want to give an initial value to the parameter; in this case we use the out parameter. The declaration of the out parameter is the same as the ref parameter. But it is used to pass the value out of a method. Now we look at the example,

class tryout  
{  
    public int mul(int a, out int b)  
    {  
        b = a * a;  
        return b;  
    }  
}  
class Program  
{  
    static void Main(string[] args)  
    {  
        tryout to = new tryout();  
        int x,y;  
  
        x = to.mul(10, out y);  
        Console.WriteLine("The output is: "+x);  
        Console.ReadLine();
    }  
}

The Output will be,

Working With Ref And Out Parameter In C#

To know more about Out parameter, follow below articles


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