Params Keyword in C# With Examples

Last updated on March 7th, 2024 at 02:06 am

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

What are params in C#?

The params in C# allows a method to accept a variable number of arguments. Think of it as a flexible way to pass multiple values to a function without specifying the count. Here’s how it works:

• When you define a method parameter with params, it acts as an array of objects.
• You can pass any number of arguments of any type to the method.

Syntax of params keyword:

The params keyword in C# is used in the method parameters to allow for a variable number of arguments. Here’s the syntax:

public void ExampleMethod(params dataType[] parameterName)
{
    // Method body
}

• dataType: Specifies the data type of the parameters.
• parameterName: Represents the name of the parameter array.

Params example with int data type:

public void PrintNumbers(params int[] numbers)
{
    foreach (int num in numbers)
    {
        Console.WriteLine(num);
    }
}

In this example, the PrintNumbers method can be called with any number of integer arguments, and the params keyword allows flexibility in passing a variable number of parameters.

Example 1: C# Params with Integer

The following code example demonstrates the params keyword in C# to specify method parameters that accept multiple integer 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 parameters 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
        }
    }
}

Important Points About Params Keyword in C# :

• The Params keyword is useful when the developer doesn’t know the number of parameters to use in advance.
•  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.

Example 2: C# Params Keyword 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 users to pass in a string formatted to their requirements and the number of parameters for the values to insert into the String.

You can imagine that if the params keyword did not exist, then the String.Format() would require an infinite number of overload methods.

Difference between params and arrays in C#

Here is a tabular comparison between params and arrays in C#:

FAQs:

References: MSDN-params (C# Reference)

Conclusion

In this article, we discussed the params keyword with multiple examples.

The params keyword simplifies method signatures, making them more readable and flexible.
Whether dealing with integers, strings, or custom objects, params empower you to handle variable argument lists easily in a method.

I hope you enjoyed and found this post about the params keyword useful. If you have any questions or comments, please leave them in the comments section below.

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Shekh Ali

Meet Sheikh Ali, a skilled Software engineer and passionate a blogger. He enjoys sharing his expertise in C#, Java, SQL, Design Patterns, and other related topics through his writing. When he's not coding, Sheikh Ali can often indulge in his passions for reading books and fitness training.

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