Params Keyword in C# With Examples

The params keyword in C# is used to specify a method parameter that can take a variable number of arguments. Generally, params work as a single-dimensional array of objects.

C# params are useful when you declare a method and don’t know how many arguments will be passed as parameters.

Important Points About Params Keyword :

• params keyword is useful when the developer doesn’t know in advance about the number of parameters to be used.
• The params parameter type must be declared as an array. Example: MyMethod(params int[] arr);
• Only one params keyword is allowed to be declared as a method parameter.
• The length of params will become zero if no arguments are passed.
• A params parameter must be the last argument in the method’s parameter list. Example: MyMethod( int a, int b, params int[] arr)
• params cannot have a default value assigned. Example: params int[] arr= 10;
• The params parameter accepts a comma-separated list of arguments of the type of the array elements.
• params keyword can’t be used with the combination of ref and out.

C# Params Keyword Example

The following code demonstrates how to use the params keyword in C# to specify method parameters that accept multiple arguments.

Here, we have created a method called AddNumbers with the params parameter and called it with an array of numbers. This method sums all the numbers passed as parameter and returns the total sum as the result.

// C# program to demonstrate the params as a method parameter in C#
using System;
namespace Params_Keyword_Example
{
    class Program
    {
        // Params Parameter  
        public static int AddNumbers(params int[] arr)
        {
            int sum = 0;

            foreach (int num in arr)
            {
                sum += num;
            }
            return sum;
        }
        public static void Main(string[] args)
        {
            int total = AddNumbers(10, 20, 30, 40);
            Console.WriteLine($" Sum: {total}");
            Console.ReadLine();
            // Output:
            // Sum: 100
        }
    }
}

C# Params Keyword Example With Object Type

The following C# code example will show you how to pass different values to a method using params of object type.

class Program
    {
        // Params Parameter  
        public static void Print(params object[] arr)
        {          

            foreach (var item in arr)
            {
                Console.WriteLine($" {item} ,");
            }
        }

        public static void Main(string[] args)
        {
            Console.WriteLine($"*** Print params elements ***");
            Print("INDIA","USA","FRANCE", 10, 20.5);           
            Console.ReadLine();           
        }
    }

Output:

Can you give a good example of the params keyword?

A good example of using params is the String.Format() method. This method allows a user to pass in a string formatted to their requirements, as well as numbers of parameters for the values to insert into the string. You can imagine, If the params keyword did not exist, then the String.Format() would require an infinite number of overloads methods.

FAQ

References: MSDN-params (C# Reference)

Conclusion

In this article, we discussed about the params keyword along with multiple example.
I hope you enjoyed and found this post useful about params keyword. If you have any questions or comments, please leave them in the comments section below.

Related articles:

• C# Array Vs List
• ref and out keyword
• C# Dictionary with Examples
• C# List Class With Examples
• C# Abstract class Vs Interface
• C# Struct vs Class
• C# Hashtable vs Dictionary
• C# Nullable types: How do you work with nullable types in C#?

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Shekh Ali

Meet Shekh Ali, a skilled Software engineer and passionate blogger with an MCA degree and 8+ years of experience in the field. He enjoys sharing his expertise in C#, Java, SQL, Design Patterns, and other related topics through his writing. When he's not coding, Shekh Ali can often indulge in his passions for reading books and fitness training.

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