Difference Between Ref And Out Keywords In C#

The ref and out keywords within C# are employed for passing arguments to a method by reference, enabling the method to make changes to the original variable provided to it.

What is the Ref Keyword?

In C#, the "ref" keyword is a reserved term. It is employed to transmit arguments by reference to a function or method, as opposed to transmitting them by value. Consequently, modifications applied to the parameter inside the method will impact the initial variable provided to the method.

Syntax:

It has the following syntax:

Example


public static void method_name(ref int x)

✅ public: The term "public" indicates the ability to access the method outside the class.
✅ static: When a method gets assigned as "static" , it indicates that it is part of the class and not specific instances.
✅ Return Type: The term "void" indicates that the method used returned nothing.
✅ parameter: The 'ref int x' designates a single int-type parameter with the name x. The argument type int is preceded by the ref keyword, which indicates that x is passed by reference. This implies that any changes made to 'x' within the method will have an effect on the variable that was passed to it.

Example:

Let's consider an example to demonstrate the use of the Ref keyword in C#.

Example


using System;
class Demo
{
public static string GetNextItem(ref int num)
{
    string returnString = "Next-" + num.ToString();
    num += 1;
    return returnString;
}
static void Main(string[] args)
{
    int q = 1;
    Console.WriteLine("The Previous value of integer 'q' is:" + q.ToString());
    string test = GetNextItem(ref q);
    Console.WriteLine("The Current value of integer 'q' is:" + q.ToString());
}
}

Output:

Output


The Previous value of integer 'q' is:1
The Current value of integer 'q' is:2

Explanation:

In this code, the GetNextItem function appends "Next-" to the provided number, increments the integer, and then provides the combined string. The demonstration in the Main function showcases the manipulation of the integer variable "q" both internally and externally due to passing it as a ref parameter.

What is the Out Keyword?

In C#, the "out" keyword is employed to send arguments by reference. Methods in C# that specify output parameters make use of the out keyword. This keyword facilitates the return of multiple values from a method. By using the out keyword to define a parameter, the compiler is informed that the method is intended to assign a value to that parameter before returning. Unlike "ref" parameters that require initialization before passing to a method, parameters marked with the out keyword do not need to be initialized beforehand but must still be assigned a value within the method.

Syntax:

It has the following syntax:

Example


public static void method_name(out int x)

✅ public: The term "public" indicates the ability to access the method outside the class.
✅ static: When a method gets assigned as "static" , it indicates that it is part of the class and not specific instances.
✅ Return Type: The term "void" indicates that the method used returned nothing.
✅ Parameter: 'out int x' defines a single int-type parameter named x. The int parameter is preceded by the out keyword, which indicates x as an output parameter. It indicates that before returning, the method is supposed to assign a value to x.

The out parameter differs from a standard parameter as it does not require any initial values to be assigned before being passed to the method. Instead, the method takes on the responsibility of initializing it before finishing its execution.

Example:

Let's consider a scenario to demonstrate the use of the Out keyword in C#.

Example


using System;
class Demo
{
public static string GetNextItem(out int q)
{
    q = 2;
    string return_Text = "Next-" + q.ToString();
    return return_Text;
}
static void Main(string[] args)
{
    int j = 1;
    Console.WriteLine("The Previous value of integer j:" + j.ToString());
    string str = GetNextItem(out j);
    Console.WriteLine("The Current value of integer j:" + j.ToString());
}
}

Output:

Output


The Previous value of integer j:1
The Current value of integer j:2

Explanation:

In summary, the GetNextItem function alters the out parameter 'j' to 2, and the Main procedure displays this modified value to illustrate the usage of 'out' parameters in C#.