Ref And Out keyword In C#

int x = 4;
int x1 = x; // This assigns the value of x (which is 4) to x1.
// Now, if you want to change the value of x to 100, you can do this:
x = 100; // This updates the value of x to 100.

using System;
class Program
{
    static void Main()
    {
        int x = 10;
        Show(ref x);
    }
    static void Show(ref int x)
    {
        // Method declaration
    }
}

using System;
class RefDemo
{
    public static void Show(ref int number)
    {
        number = 23;
    }
    static void Main()
    {
        int x = 10;
        Show(ref x);
        Console.WriteLine(x); // This will print 23
    }
}

using System;
class RefDemo
{
    public static void Show(ref int number)
    {
        number = 23;
    }
    static void Main()
    {
        int x = 10;
        Show(ref x);
        Console.WriteLine(x); // This will print 23
    }
}

Case 1

using System;
class GradeData
{
    public string name;
}

class RefDemo
{
    public static void Show(GradeData data)
    {
        data.name = "SURYA";
    }

    static void Main()
    {
        GradeData obj = new GradeData();
        GradeData obj1 = new GradeData(); // Create a new instance of GradeData
        obj1.name = "Rajani";
        obj1 = obj; // Assign obj to obj1

        Show(obj1); // Pass obj1 to the Show method
        Console.WriteLine(obj1.name); // This will print "SURYA"
    }
}

Consider the second case.

Case 2

using System;
class GradeData
{
    public string name;
}
class RefDemo
{
    public static void Show(GradeData data)
    {
        data = new GradeData(); // Create a new GradeData object
        data.name = "SURYA";
    }
    static void Main()
    {
        GradeData obj = new GradeData();
        GradeData obj1 = new GradeData();
        obj1.name = "Rajani";
        obj1 = obj; // Assign obj to obj1
        Show(obj1); // Pass obj1 to the Show method
        Console.WriteLine(obj1.name); // This will print "Rajani" because obj1 still references the same object as obj
    }
}

Example

using System;
class GradeData
{
    public string name;
}
class RefDemo
{
    public static void Show(ref GradeData data)
    {
        data = new GradeData(); // Modify the object referred to by data
        data.name = "SURYA";
    }
    static void Main()
    {
        GradeData obj = new GradeData();
        GradeData obj1 = new GradeData();
        obj1.name = "Rajani";
        obj1 = obj; // Assign obj to obj1
        Show(ref obj1); // Pass obj1 by reference to the Show method
        Console.WriteLine(obj1.name); // This will print "SURYA" because obj1 now references a new object
    }
}

Due to the use of the ref keyword, the C# compiler treats the data object as a copy of the obj1 type, so any changes made to the data are reflected in obj1/obj.

Note. Before we use the ref keyword in a call a method, it must be initialized, whether it is a value type or a ref type.

Out keyword in C #

The out is also used for the same purpose, and we can use it for both a value type and a reference type, but the following is the main difference.

Before calling the method using the ref keyword, we must allocate the variable used in that method, whereas for an out, we need not assign the value before calling the method. In other words, the C# compiler does 't care about whether you are assigned or not, but it is necessary when the controller goes to a specific method. In that method, we must initialize the variable before the control flows out of that method.

Another difference is that when out is used with a value type, then we can return more than one value from a method at a time.

Example

using System;
class OutDemo
{
    public static void GetData(int c, out int a, out int b)
    {
        a = c + 5;
        b = c + a;
    }
    public static void Main()
    {
        GetData(5, out int a, out int b);
        Console.WriteLine(a);
        Console.WriteLine(b);
        Console.ReadLine();
    }
}

Important Key Capsule

Remember that during compilation, both the out and ref keywords are not considered by the CSC compiler. It only checks the standard language infrastructure, so if you are writing like this.

public static void GetDataRef(ref int a)
{
    // Your code here
}
public static void GetDataOut(out int a)
{
    // Your code here
}

If and think that it is an overloaded method, then you are wrong. Both are the same only. Here the C# compiler does not consider ref and out as a parameter, so it shows an error at runtime.

I think the preceding has given you a clear picture of ref and out.

Thanks for reading. I hope this is useful for you.